Sn95 Gt Rear end in ‘91 Fox 5.0

Artemisia22

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Jul 6, 2022
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Howdy, I still have the stock rear end in my ‘91 5.0 and I’m looking to 5 lug swap it. I have seen other threads touch on the topic but I want to ask the detailed questions about swapping the Gt Sn95 rear end to the fox body.

Will everything screw into the frame when doing the swap?

What brake lines and brake system (stock brake booster or hydroboost) should I run?

Also, will the brake system make me have to swap the front end out of an sn95? Or do I swap the stock 4 lug spindle to a 5 lug spindle (along with rotors) and call it a day?

Does the stock shaft connect directly to a 94-98 Gt rear end ?

Once the swap is done, am I limited in suspension options ? As in, do I have to use fox specific suspension or sn95 suspension dimensions; will the sn95 suspension connect directly to mounting points?

I saw in another thread that the rear end swap comes along with “moving it negatively in order to fit the tires under the car.” I’m not sure that that means. Also, not looking to weld anything in case that comes up.

I know it’s been quite a mouthful but help, tips, experience is appreciated!
 
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Mustang5L5

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Feb 18, 2001
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If you swap in a 94-98 GT rear end, it’s a direct bolt-in with a few minor things to address.

The disk brakes add 0.75” to each side. There are bracket kits and axles out there that will correct this and allow for running stock fox offset.

Depending on the year, the brake lines run differently. 94-95 are on the axle, 96+ is body mounted if the car has ABS. There are kits to mount the brake lines like the fox, using 94-95 soft line brackets.

Do not use a 99+ sN95 rear axle as the housing itself is wider.

All the calipers on every 94-04 setup are the same 38mm units, so what mc and booster you run all depends on what front brakes you have. No need to go hydroboost.
 
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92_DynoFox

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Jan 11, 2023
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Howdy, I still have the stock rear end in my ‘91 5.0 and I’m looking to 5 lug swap it. I have seen other threads touch on the topic but I want to ask the detailed questions about swapping the Gt Sn95 rear end to the fox body.

Will everything screw into the frame when doing the swap?

What brake lines and brake system (stock brake booster or hydroboost) should I run?

Also, will the brake system make me have to swap the front end out of an sn95? Or do I swap the stock 4 lug spindle to a 5 lug spindle (along with rotors) and call it a day?

Does the stock shaft connect directly to a 94-98 Gt rear end ?

Once the swap is done, am I limited in suspension options ? As in, do I have to use fox specific suspension or sn95 suspension dimensions; will the sn95 suspension connect directly to mounting points?

I saw in another thread that the rear end swap comes along with “moving it negatively in order to fit the tires under the car.” I’m not sure that that means. Also, not looking to weld anything in case that comes up.

I know it’s been quite a mouthful but help, tips, experience is appreciated!

If you swap in a 94-98 GT rear end, it’s a direct bolt-in with a few minor things to address.

The disk brakes add 0.75” to each side. There are bracket kits and axles out there that will correct this and allow for running stock fox offset.

Depending on the year, the brake lines run differently. 94-95 are on the axle, 96+ is body mounted if the car has ABS. There are kits to mount the brake lines like the fox, using 94-95 soft line brackets.

Do not use a 99+ sN95 rear axle as the housing itself is wider.

All the calipers on every 94-04 setup are the same 38mm units, so what mc and booster you run all depends on what front brakes you have. No need to go hydroboost.

Hey @Mustang5L5 . Thanks for these helpful tips. I am going to start the conversion on mine as well with a 95 GT differential for my 92 foxbody 50. I am curious where I can find those bracket kits to help correct the extra .75" on each side.

Also what did you mean by Hydroboost. This same guy who is selling me the 95 GT differential is proving me the dual piston front calipers with 94/95 spindles and says he has the cobra master cylinder & brake booster. But based off the research i've done I am not sure which parts I need. Also I might need a proportioning valve & plug? Any insight you have would be awesome!!!
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
39,704
15,486
224
Massachusetts
Hey @Mustang5L5 . Thanks for these helpful tips. I am going to start the conversion on mine as well with a 95 GT differential for my 92 foxbody 50. I am curious where I can find those bracket kits to help correct the extra .75" on each side.
You'll need brackets and axles.

Brackets here

LMR also sells the North Race Cars brackets too

and the axles which feature the SN95 flange end
or



Also what did you mean by Hydroboost. This same guy who is selling me the 95 GT differential is proving me the dual piston front calipers with 94/95 spindles and says he has the cobra master cylinder & brake booster. But based off the research i've done I am not sure which parts I need. Also I might need a proportioning valve & plug? Any insight you have would be awesome!!!


Hydroboost is the booster setup Ford used on the 96+ V8 cars because there wasn't enough room to run a vacuum booster. I was responding to the OP's question regarding needing to convert to hydroboost. It's not a necessity for newer brakes.


That combo is tried and true
99-03 dual piston PBR's
SN95 rear brakes
93 Cobra 1" MC
booster

and yes, you will need to plug the stock prop valve and install an adjustable...well, at least it's recommended.