New differential recommendations for 9"

"66stang" wrote

Depends on what you're using it for. Street performance- 3:70's, highway-

3:00's, drag 4:11's

yes

I had mine completely rebuilt for $400 and that was fair. If you already have the new gearset then I would imagine it would be less since all they gotta do is drop it in and check the lash (well basically).

A '66 would have a 9" only if it came with the K code HiPo.

The True Trac torsen is the best lsd out there.

Most -- nearly all -- 9" have 28-spline axles.

I paid close to $900 to have an Auburn diff and some Richmond gear

3.55's installed in a 8". I would expect the True Trac to cost more than the Auburn, but you didn't mention gears.

180 Out

The guy I purchased the car from installed the 9" and 3.55's. I should check to make sure that they really are though. I will most likely reuse the current gears so I'm really just looking for a differential.

For your use, the stock Ford rebuilt LSD is plenty strong enough, quiet, works well, and is reasonably priced. You can pay more for something like an Auburn; but why would you?

It might be strong enough for him, but a stock 9" LSD is about the weakest LS unit around.

Al

Sometimes upgrading to a stronger part isn't the best idea. You end up spending more money and going to more effort with no advantages. For a stock 5.0, a stock 9" is plenty strong enough to last for 100,000 miles. You could spend an additional $300 for a stronger diff, but it will still work invisibly for 100,000 miles. You haven't gained any advantage for the additional expense. Same thing with axles, springs, shocks, etc. You can spend a lot of money to get a "stronger" part, but you don't gain anything. No value added. Save the money and use it for something worth while - like better seats. OTOH, if future plans call for a stronger motor, drag slicks, or a class III trailer hitch, then it's worth while to go for the stronger parts now.

Where is the cheapest place to buy a Trac-Loc unit? All the ones I have seen are only about $100 cheaper than the Detroit Truetrac or the Auburn Pro Series.