Gifted a Junk 1976 Mustang II with plans for a radical conversion!

MXGerry · Apr 29, 2025

Greetings from Central Mexico. Recently I was "gifted" with a junk and stripped 1976 Mustang II having a supposed 302 engine with a four-speed transmission and 8 inch rear end. As it is already stripped inside and out, my goal is to convert it to APPEAR as an open-wheel or asphalt circle track Modified which often used Mustang II or Pinto bodies. This vehicle will be street legal by Mexico's loose standards and used for parades and promotion purposes.

My plan is to re-enforce the unibody construction with metal laminates (top and bottom) plus increase structural integrity with some form of a "safety" cage. The cockpit will only have two seats with a full, smooth metal interior.

MAJOR QUESTIONS!
1) Can the original points of mounting the engine, transmission, rear leaf springs etc. be re-enforced and used?
2) Are there any stock Ford/Mercury components such as replacing the iron 302 head and carbureted intake manifold with lighter aluminum? Upgrade of the stock four-speed transmission mated to the 302 engine? Upgrades to the 8 inch rear end? etc.

THANKS IN ADVANCE!!
MXGerry

Noobz347 · Apr 29, 2025

I am sensing some contradictions:

Is it a parade vehicle or an off-road HP monster?

MXGerry · Apr 29, 2025

Noobz347 said:
I am sensing some contradictions:

Is it a parade vehicle or an off-road HP monster?

This will be a parade and promotion vehicle. It would be an expensive undertaking to add a full chassis and safety cage. The stock V-8 302 cid engine was only rated at about 135 HP. Adding 100 HP with a reduction in weight and a good suspension should make it feel sporty.

Noobz347 · Apr 29, 2025

I vote for this:

It looks sporty.

MXGerry · Apr 29, 2025

My "inspiration"...

LILCBRA · Apr 29, 2025

Welcome to the group!

To try and answer some of your questions to the best of my ability....

The stock engine mount locations should be sufficient as long as you're not intending to go with an insane amount of power. My car uses all stock mounts (well, the transmission crossmember has been modified....) and holds a 302 with 265hp/300lbft at the wheel. This also applies to the rear.

IF (and this may be a big if....) you're able to find a mid 80's 5.0 HO, they were equipped with aluminum intake manifolds. You'll be out of luck sourcing a stock Ford aluminum head UNLESS you go with one of their aftermarket offerings.

The 8 inch rear can be upgraded almost as easily and readily as a 9 inch. There are a number of vendors that offer differentials, gears, and axles should you decide to go that route.

A more readily available and more stout (than the original 4 speed....) T5 can be swapped pretty easily as long as you have all of the proper accompanying parts (bell housing, flywheel, pedals, etc....) - there have been a number of IIs with T5's swapped, mine included.

I think I hit on all of your posted questions. If not, or if you have more, post them up!

MXGerry · Apr 29, 2025

THANK YOU!

78CobraII · Apr 30, 2025

The Number 9 car is probably your best bet for a reasonable project. Lower the car a little, use wide tires and wheels, cut the fenders to fit the tires.

The other 2 cars would require building a dedicated frame to get the car that low.

Maybe you could remove the front fenders, but I would not remove the inner fender panels as they are structural. Unless you want to replace them with a structural bar on both sides of the engine compartment that runs from the firewall to the fraternal.

With wider tires and wheels up front, you definately need power steering!

Once you get it low and with wide tires and wheels, you might as well take it Autocrossing!

MXGerry · Apr 30, 2025

78CobraII said:
The Number 9 car is probably your best bet for a reasonable project. Lower the car a little, use wide tires and wheels, cut the fenders to fit the tires.

The other 2 cars would require building a dedicated frame to get the car that low.

Maybe you could remove the front fenders, but I would not remove the inner fender panels as they are structural. Unless you want to replace them with a structural bar on both sides of the engine compartment that runs from the firewall to the fraternal.

With wider tires and wheels up front, you definately need power steering!

Once you get it low and with wide tires and wheels, you might as well take it Autocrossing!

There are no front fenders. The plan is to add to the sides of the hood to have a half fender or attach a half fender to the inner fender. I desire to show off the tubular suspension, a bit of the engine and the tubular exhaust header.
As I will be replacing all the suspension, I have an option to use standard height front spindles or drop them two inches. I need to research here if anyone ran into problems using drop spindles.
THANK YOU!

LILCBRA · Apr 30, 2025

Wow - that's rough....

I'd see if you couldn't locate a pair of front fenders of some sort, cut them as you see fit, but leave the front around the headlight buckets more or less intact. Then, you can see about locating a header panel and have what looks to be a complete car. Having no fenders will complicate the front end some unless you're looking to do something completely custom - like a round tube "bull bar" type thing to attach some off road lights or something. Maybe you could use some rectangular thin wall steel tube and construct a bumper to weld the "bull bar" to as it appears the bumper mounts/shocks are still in place. Something very loosely based on this:

That would give your radiator some semblance of protection.

You know, this is really taking on a battle car vibe....

Really looking forward to your creation now!

MXGerry · Apr 30, 2025

LILCBRA said:
Wow - that's rough....

I'd see if you couldn't locate a pair of front fenders of some sort, cut them as you see fit, but leave the front around the headlight buckets more or less intact. Then, you can see about locating a header panel and have what looks to be a complete car. Having no fenders will complicate the front end some unless you're looking to do something completely custom - like a round tube "bull bar" type thing to attach some off road lights or something. Maybe you could use some rectangular thin wall steel tube and construct a bumper to weld the "bull bar" to as it appears the bumper mounts/shocks are still in place. Something very loosely based on this:

That would give your radiator some semblance of protection.

You know, this is really taking on a battle car vibe....

Really looking forward to your creation now!

The radiator and a large coolant tank will go into the trunk to keep the heat away from the passengers as the car's primary function will be used in parades. I still have the original headlights and square chrome trim around the headlights plus rear tail lights. My thought is to have a rectangular grille in front of the engine to replicate the original Mustang II.

LILCBRA said:
You know, this is really taking on a battle car vibe....

Really looking forward to your creation now!

The radiator and a large coolant tank will go into the trunk to keep the heat away from the passengers as the car's primary function will be used in parades. The original fan and coolant pump will be replaced by electric pump(s) I still have the original headlights and square chrome trim plus rear tail lights. My thought is to have a rectangular grille in front of the engine to replicate the original Mustang II.
Both front and rear bumpers (heavy!) will be replaced with chromed tubing.

MXGerry · May 2, 2025

Mustang II is almost completely stripped of all bolt-on parts. Tomorrow or Monday it is attached to a "rotisserie" to allow full 360 degree access to the bare unibody.
Plans are to keep the current 302 engine but rebuild it and add mild (affordable) performance parts. Perhaps used aluminum cylinder heads to save weight. A four venturi Holley carburetor from my friend at Air Fuel Spark mounted on an aluminum manifold.
The transmission will be a performance modified C4.
I would love to ditch the HEAVY cast iron rear end and leaf springs! ha ha haa
MXGerry

LILCBRA · May 2, 2025

MXGerry said:
Mustang II is almost completely stripped of all bolt-on parts. Tomorrow or Monday it is attached to a "rotisserie" to allow full 360 degree access to the bare unibody.
Plans are to keep the current 302 engine but rebuild it and add mild (affordable) performance parts. Perhaps used aluminum cylinder heads to save weight. A four venturi Holley carburetor from my friend at Air Fuel Spark mounted on an aluminum manifold.
The transmission will be a performance modified C4.
I would love to ditch the HEAVY cast iron rear end and leaf springs! ha ha haa
MXGerry

I guess it depends on how heavily you'd like to get into fabricating stuff for the car. I don't know what weight difference there would be, if any, but you could always swap an 8.8 rear in place of the 8 inch. Then you could also fabricate some sort of performance rear suspension - I'm thinking something along the lines of a custom four link and coil overs. I'm not sure how much weight would be saved, but I'd think you'd end up with more adjustability if you wanted/needed it.

Noobz347 · May 2, 2025

The thing that keeps popping into my mind with this thread:

Chassis Swap

I mean, through Mexico, Cali, Arizona, TX, and OK, there [has] to be maybe a Bronco, Bronco II, or some other chassis that would get you [closer] to what you want.

Hell... A fully tubular dune buggy chassis would be a [huge] score. Just weld the II body to it after you get the drivetrain and suspension squared away.

Just thinking out loud...

Noobz347 · May 2, 2025

On a side note:

I just did a Craigslist search for "Dune Buggy" in my area and got (aside from the junk that doesn't apply):

How do you feel about an open header, rear-mounted, 302 with a thumpy cam?

It supposed to attract attention right? Should be loud as eff!

MXGerry · May 2, 2025

Noobz347 said:
The thing that keeps popping into my mind with this thread:

Chassis Swap

I mean, through Mexico, Cali, Arizona, TX, and OK, there [has] to be maybe a Bronco, Bronco II, or some other chassis that would get you [closer] to what you want.

Hell... A fully tubular dune buggy chassis would be a [huge] score. Just weld the II body to it after you get the drivetrain and suspension squared away.

Just thinking out loud...

A vehicle with a full chassis was also my priority. It is my nephew who has a mechanic and fabricating shop who "gifted" me the Mustang II. All of the "hard points" of the chassis appear to be strong. It is all the inner sheet metal which needs cut away or covered with laminate to seal the cockpit and the trunk area.

MXGerry · May 17, 2025

May 17 UPDATE....
Rotisserie constructed using box tubing. Mustang II is stripped of all removable weight, carried into the shop by six people, then attached to the rotisserie. We used the old steering wheel and shaft on the rotisserie to turn the Mustang II body from side to side. Two days of scraping away black sealer, 49 years of dirt and grease and now the cutting away of cancer!
The "hard point" locations where the rear leaf springs are attached will be retained. I will search for a lighter differential (7.5 inch?) having a 4:10 ratio as this will not be an all out performance build. It won't matter if comes with drum or disk brakes.
Front suspension will be replaced by a kit having modern tubular A-frames, spindles, disk brakes, etc. as aftermarket companies copied the Mustang II design for use in street rods.
I will search for a 1970s-80's C4 or C5 automatic transmission for ease of driving.
The Title shows this Mustang II came with the V-8 302 engine. Upon inspection, it appears to have a fresh rebuild and the casting numbers for the cylinder heads show 1975. They may be the larger combustion chamber (low compression) heads and will be discarded for other better smaller chamber OEM heads. I would love to get a set of aftermarket aluminum heads to save weight but it isn't in the budget. The cast iron intake manifold will be discarded for a lighter aluminum manifold. Air Fuel Spark (AFS) will supply a vintage Holley carburetor.
THANKS!
MXGerry

Noobz347 · May 17, 2025

MXGerry said:
I will search for a lighter differential (7.5 inch?)

SOLD Thread '7.5" complete rear end from 83 mustang $25 SOLD'

Mar 30, 2025

This is out of my 83 mustang and as far as I know its in running condition... Was my sisters car and when it stopped running she put it in the garage 20 years ago...
I believe it is a 3.07 ratio.... EVERYTHING is included.. Slapper bars, brake lines, Brakes and drums.....
Located in Lakeland, Florida...... $25 takes all...
NO shipping, pickup only....
Has been stored in my garage until a few days ago....

MXGerry · May 17, 2025

Thanks for the kind offer. $25 Dollars is a bargain for sure.
As I live in Central Mexico... Perote Veracruz... I need to search for a differential nearby.
MXGerry

MXGerry · Aug 3, 2025

August 3 Update...
Rectangular tubing now connects the front stub with the rear stub. Flooring has been replaced with 10 gauge diamondplate steel. Doors are welded into place and window openings enlarged to allow easy entry and exit. Paint and old "bondo" have mostly been stripped away. Lower body corner pieces which held side lights have been removed with metal patches cut from them to replace lower body corrosion.

Gifted a Junk 1976 Mustang II with plans for a radical conversion!

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