Hi,

I have a 1968 Mustang fastback. I would like to have Positraction, and change my Gear Ratio. I presently have 3.05 (28 splines) 8" or 8.8". Can anyone tell me how to tell how many inches. I would like to change it to 3.73. Should I just change the Diff, the gears, or can I get one from another Ford Model ?

Thanx

 

I can't help you on the size of your diff. - I'm not really sure what size it is and wouldn't want to send you in the worong direction.

Positraction is GM terminology. Ford terminology is TRAC-LOCK or traction lock - this will be important when you start your hunt for replacement parts.

Lots of Ford Mustangs (almost all V6 models anyways) came with a 7.5 inch open differential carrier (in other words you can only do a burn out with one wheel). Ford Racing Parts has come to the rescue offering Traction Lock Diffs. for many applications - no need to replace your whole rear end either ... just the diff. needs to be changed. Try here:

Mustang Traction-Lok / Differential at LRS - Same Day Shipping!

 

A 68 Mustang would be equipped with an 8" rear axle, assuming that it is a factory small-block powered car. That type of axle wasn't used passed about 1980 model year. You can buy aftermarket replacement gears and traction-lock differentials for the 8" from various sources, but they aren't cheap like the late model Mustang 8.8" stuff.


cheers
Ed N.

 

it could be a 8 or 9 inch rear.the pig falls out the front as a complete assembly.there is no rear end cover.gears are easy to get .drop the pig out and read the info on the ring gear.THEN order your gear.this is the safest method of making sure you have the proper gear.

 

The 68 Mustangs with a 302-4V and 3.25 axle ratio got a 9 inch but otherwise you would have an 8 inch.