7.5 or 8.8 rear end?

[Rdrcr]

My quick search did not help me find an answer. Is there any way to verify if my '86 GT has a 7.5 or 8.8 rear end without taking it apart? I would like to get some 3.55 gears installed this weekend and want to be sure that the correct parts are ordered.

Mike

 

[NIKwoaC]

an 86 GT should have an 8.8 unless someone for some godforsaken reason swapped in a 7.5

you can also check the axle tag, VIN, etc

 

[Rdrcr]

^^^^
Is there a digit in the vin # or rear end that will tell me? It was my understanding that my car should have the 8.8, but I would hate to tear things apart only to find that my assumption was wrong.

Mike

 

[samickguy15]

Check the door tag. That should have an axle code. There should also be a tag on one of the cover bolts on the axle. It will read something like 2L73 8 8 or 3 55 7 5, etc. First series of digits is gear ratio, second set is ring gear diameter. Also, the 8.8 has 4 flat edges on the cover while the 7.5 has two visually.

 

[Rdrcr]

^^^^
Very cool, I'll check it out.

Thanks

Mike

 

[85_SS_302_Coupe]

Sorry i'm a bit late on this one. You can identify it by looking at the bolt pattern on the diff cover.


EVERYONE right click/save as:

7.5:

8.8:

As you can see, the 7.5 is sort of oval shaped while the 8.8 is more of a rounded square kind of shape. Note that they have the same number of bolts too so that doesn't give any hints. Hope that helps.

 

[PUNISHER RACING]

EVERYONE right click/save as....................That kills me you know it happened to!

 

[Roland69]

cant you measure from the top to botom

 

[SuperStang83]

They came stock with 8.8

 

[bloopbloob]

why measure? just listen to 85_SS_302_coupe! if you look at them, the difference is obvious immediately!!! a 7.5 will have 2 flat sides.

 

[SVT32VDOHC]

The 8.8 will have quad shocks on it, and the 7.5 won't.

 

[Rdrcr]

Yep, thanks guys. 8.8!

Mike

 

[85_SS_302_Coupe]

The 8.8 will have quad shocks on it, and the 7.5 won't.

True...some of them had "slapper bars" but i have no idea what years had them. I literally have 0 experience with a 7.5 aside from the 7.5 pumpin in the IRS on my Merkur.

 

[SuperStang83]

Thanks for the handy diagram 85!

 

[SVT32VDOHC]

The 7.5" can be built up, but why bother? You can always weld the quad shock brackets on the axle housing of the 7.5 I guess.

 

[85_SS_302_Coupe]

The 7.5" can be built up, but why bother? You can always weld the quad shock brackets on the axle housing of the 7.5 I guess.

Yeah, back in the day it was all about a 7.5 with a Detroit locker in it, unless you had the cash for a 9 inch. Now you can build up an 8.8 to be just as strong or stronger than any 9 inch.

 

[jspagna1]

Yeah, back in the day it was all about a 7.5 with a Detroit locker in it, unless you had the cash for a 9 inch. Now you can build up an 8.8 to be just as strong or stronger than any 9 inch.

Yes, the 8.8 will be cheaper than a 9" and is very strong. You could compare it to GM's 12 Bolt Posi rearend.