I'm doing the infamous conversion from an '88 LX 4 banger to an 8 cylinder and am starting with the rear end. Yes, I know just buying a junked 5.0 and starting from there would be easier and cheaper, but I would rather work on this one (pointless and costly sentimental value..first car).

I've read a few posts and tech articles that say the 7.5 is fine if you're not doing massive drags or are putting out a lot of HP. They say that you can just put a trac lock gear set in to get the grab. I plan on having a daily driver that I will slowly upgrade over a few years, but for the time being I don't plan on breaking 400 HP.

Do I need to upgrade from a 7.5 to an 8.8, or can I simply buy new gears?

Also, how much better is a 9 than an 8.8?

If it changes anything, I would like rear discs; I prefer the look and maintenance over drums.

Any help is appreciated by this new guy!

 

8.8

enoguh said

 

If your staying around 400hp and not put slicks on it .You should have no problem with a 8.8

 

82-5 gt's came with 7.5's, the 8.8 is better but for daily use a 7.5 works till you can find a good
8.8 to drop in

 

9 is best as far as holdin up to hp.. 8,8 then 7.5///i had 350 hp on a 7.5 for a few years as a daily driver and held fine....but when i passed the 400 mark i put a 8.8 410s...im in process in another car of a narowwed 9 inch... its notthe inside usually that breaks its the weldings on outside that break///altho i have shatterd 7.5s in past with to much torq....with 345 traction lock..i have had over 400 hp with a 8.8 rear and has lasted me 4 yrs now,and a few passes on strip...onot including the 100 juice..all in the workmanship....any1 can put somthin together,takes skill to build it...

 

The 8.8 is pretty bullet proof, needs 31 spline diff. and axles though.

 

my 84 has a 7.5 in it and i beat the **** out of my car but she likes it. i recently found out that where the diff breather is was missing and i have been leaking fluid and i am probably pretty low and she still took the abuse how ever im going to get the ford racing 8.8 that comes with 3.73's already in it ready to bolt in for about 800-900 new

 

So it sounds like i definitely need to drop the 7.5 out, but what kind of price difference am i looking at to get the 8.8? I'll go the salvage yard route and probably do what I need to to do a disc conversion. I looked at stangparts.com and they have used 5.0 rear ends for about 500 bucks. Is that reasonable?

 

i got my 8.8 posi from the salvage locally for 150$

 

I'll sell my stocker rearend to you (actually give, I live in CA thought.) I bought 3.73 gears in a reared for $50 2 months ago, talk about a steal.