Drivetrain 1974 v6 to v8 swap questions

Ed88

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Aug 21, 2017
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So im gonna be pulling my cologne out and putting in a 302 from a fox body. I've gone through a bunch of posts on this a few times but wanted to make sure I'm not missing anything.
I know most say to brace the frame, ok I can do that.
I know the frame mounts are hard to come by so we're gonna try away around that like a cradle or something.
Found a few bellhousings so I can keep my 4speed (no I'm not swapping transmissions)
But am I gonna run I to a problem with driveshaft length? This is my main concern. There aren't any driveshaft places near me unless I wanna go to st. Louis, which I dont want to do as Im not a fan of that city. I could be wrong but I'm assuming it might be the same length as the other II's?
Thanks in advance
Eddie
 
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LILCBRA

10 Year Member
Dec 6, 2005
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You're planning on keeping the 4 speed that was originally behind the 6 - am I understanding you correctly? If so, I think the tailshaft is a different length vs a 302 transmission. So depending on where the rear of your engine ends up compared to where the 6 was AND if there is any difference in the depth of the bell housing, that would all be a factor if your shaft needs shortened. It will also dictate where the shifter comes through the floor, where the mount ends up in relation to the transmission cross member and pilot bearing engagement. I have never installed a 4 speed from anything other than another 8 cylinder car into mine, so I don't have any solid answers for you.

How close to the Quad Cities are you? Sadler's does driveshaft work, I had them work on a driveshaft for me eons ago, did a great job.....
 
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Ed88

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Aug 21, 2017
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Well that kinda puts a wrench in things. One reason I wanna keep the 4speed other than I rather enjoy it is around where I live 302s with transmissions go from 100-300 or so for an engine to 2000+ when mated with a transmission. Finally found someone that had a 302 in pieces which is what I wanted to do so I could rebuild it. The mustang scene in southern illinois is weak lol
I'm quite a distance from the quad cities I believe. I live in the tail end of illinois
 
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StadEMS3

Active Member
Jun 19, 2003
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Go T5, you will not regret it! You can get a Quicktime bell housing and aftermarket dual hump trans bracket designed for the II as well. Not sure on V6 to V8 drive shaft lengths. I have a 74 V6 Ghia and have been thinking about a V8 swap too, but I bought a King Cobra and did the T5 swap for the V8 fun! (Driveshaft was a direct fit for the T5) The Ghia is more for slow cruising now, lol
 
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2Blue2

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Mar 5, 2019
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I think Trans dapt (pt# 4982) has engine mounts 50$ a pair now. Haven't seen em in person but not the fox mount picture anymore in ad.
+1 on the t5 instead.
The mustang ii Organization has the skinny on this swap, look @ their website.



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429MII

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Mar 10, 2019
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The 4 speeds supplied behind V8 and V6 Mustang II's were barely strong enough for the 135 hp the 302's put out. (mainly the torque that wrecks them anyway, and the cases flex under any serious load.

Most guys will tell you they have gone through a few if they have owned their car for very long..

The V6 trans has way too low of a gear to work properly with the V8 unless you have like a 2.00 rear end gear. First is like 4.0 to 1. all that torque multiplication and a V8 equals transmission confetti.

I am pretty sure the V6 is the reasonable power limit for these transmissions in reality. The V8 cars, if driven lightly can survive, but there will be no clutch dropping or crazy shifting or you will be looking for a new one, and they are not easy to find.

The simplest things and cheapest in this order are leave it a V6, or do the V8 but with automatic, or do a T5 swap as someone mentioned earlier, although I would guess you don't want to drop the coin required for a quicktime bell housing..

Stock V8 4 speed stuff for these cars is not cheap or easy to find.

IF you had a good v8 4 speed drivetrain donor car, then you could stay stock with that too, but good luck finding one of those cheap anymore either.
Everyone in Mustang land (except us Mustang II lovers) calls these cars down, but that is not reflected in the prices of parts. Good V8 stuff and Cobra pieces cost an arm and a leg.
It's much much cheaper and easier to build a budget fox body.

If you are serious about the swap without driveshaft work, the prior suggestion of the T5 is the way to go. I think the T5 would be good for around 300 ft lbs torque reliably if it is in good shape, which is probably double that of the RAD 4 speed.
Keep in mind you also only have a V6 diff and V6 driveshaft, and I believe both are lighter duty than the V8 cars. SOME of the V6 cars had the 8 inch diff, but a lot did not.
 
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