[chevymad]

I recently bought an auburn posi off of ebay for my wifes 87 formula. The previous owner had no clue and his ad showed that, but for the price I sprung for it anyway. Well I measured this carrier and compared the dimensions to ones listed on auburns site. Everything looks good there. Dimensions match exactly with the 7.5/7.625 dimensions listed. The side gears have 28 splines though so I got a set of newer 28 spline axles. Now comes the problem, the splines in the posi unit are approx. 1/8" bigger than my axles!!

I can find no part #s on this carrier. Only the US patent # and a Canada date of 1987... How can I figure out what this fits? I'd like to turn it so I can buy the proper unit...

 

[big gear head]

The 28 spline axles for the 7.5, 8.2, 8.5 GM and 9" Ford are all the same. The 7.5, or 7.6, didn't get 28 spline axles untill '89 or '90, so the date of '87 on the case makes me think that this is not a 7.5 differential. I can't think of another 28 spline axle that is larger than these. You probably need to contact Auburn and ask them how to identify it.

 

[RatLuvr]

the late model GM 8.5 10 bolts used a 28 spline axle in a car app.......could be what you have(er n/m didn't see the part from BGH about the 28 splines being all the same ).....I have a new 8.5 28 spline Lock-Rite in a box in the garage if you want I can get the dial caliper out and take some measurments but to me that sounds like what you got :\

if it is and you don't want it....are you gonna resell??

heh i just removed a auburn posi from a 94 camaro on saturday....anyone ever seen a auburn side gear crack the cone????

Peace
Matt

 

[68KMENO]

don't kill the messenger .... FORDS 8.5's have two size axles... one for the mustang & a larger one for the ranger trucks ( I'll deni knowing anything about ford)

 

[Jay72]

Originally posted by 68KMENO:
don't kill the messenger .... FORDS 8.5's have two size axles... one for the mustang & a larger one for the ranger trucks ( I'll deni knowing anything about ford)

This isn't true, i found out the hard way. Ford 8.8's use 28 spline axles in the 4.0 liter ranger and mazda B4000's and in most mustangs.
The explorers and f-150's use 31 spline axles. Why are we talking about fords

J/K

 

[chevymad]

Yes if I can ID this, I will resell. I dont think its the 8.5.. On auburns website they give external dimensions for their rears. This one matches the 7.5 in all respects cept axle size. The other size rears seem to be alot different.

As for contactin auburn.. i'm trying!!! They havent gotten back to me yet.

I've counted and recounted the splines now. Always comes to 28.. same with my axles.. Still wont fit though. Dont figure!