Any differences? I suspect a V6 one might not be posi, but would that be it? Same brakes?

If somebody was upgrading the gears and/or the posi unit anyways, it would be cheaper just to start with V6 on anyways.

 

Stephen, you looking at a 4th gen rear?

If so, go 98+. I believe all 98+ disks are the same (Considered "LS1 brakes"). Though I know my mom's 99 V6 still has drums.

If you're swapping in your own ring and pinion / posi, etc then I'd say go with a disk V6, though it won't be much cheaper if any than an LS1 rear. I got mine with everything on it for $300.00. 3.42's, Posi, calipers, rotors etc.

 

Yep!

And from research, it says the the LT1 rear end is about 1.5" wider than our 3rd gen rears but the "LS1" rear is only .75" wider, which would mean my Snypers would fit about PERFECTLY flush!

I find it kinda hard to believe, but true?

You say all 98+ has discs & are the same, but your mom's 99 has drums?

 

No, all 98+ that HAVE disks are the same disks. There's no discrepancies between the V6 and V8 disks. I didn't know the LS1 rears were that skinny. I thought they'd kick out on either side about two inches. I'll have to measure them.

 

Some V6s had posi. Look for a Y87 package (RPO code) which is like 3.42 posi I believe plus some suspension mods.

 

Physically, there's no difference in strength between a fourth gen diff and a 90-92 diff. Those use 28 spline axles. 82-89 diffs have smaller 26 spline axles. The fourth gen diffs are also about 2" wider on each side so proper backspace rims are required or the wheels will stick out. Other than that, the only other differences are gear ratios, carriers (open, posi etc) and what brakes are on it.

In the third or fourth gens, there is no such thing as a V6, V8 or LS1 etc differential. They're all the same weak 10 bolt with different gear ratios and brake options.

It will only have a posi if it has the G80 RPO code.

 

I just got a 9 bolt posi rear with disk brakes and a 3.45 gear ratio. Is there much difference in the strength of the 9 bolt compared to the 10 bolt? I've heard both ways... but which is correct?

I'm hoping to put this rear in place my stock 10 bolt posi with drum brakes and 2.73 gears. I figured it would be ok to do this swap even if the 9 bolt is weaker because I only have a stock 305, and I don't plan on upgrading the engine any time soon (budget won't allow it).

 

The 9-bolt is MUCH stronger than a 10-bolt & just shy of a stock Ford 9" rear strength.

 

but wouldn't the 10 bolt be better in the long run because there is an aftermarket for them? 9 bolts don't have any aftermarket other then gears.

 

Lot more the JUST gears...For example... http://www.9bolt.com/

If you are worried about blowing up your rear end often & needing parts, stay with a 10 bolt. If you want strength to start with, use the 9 bolt.

But the 91/92 10 bolts & the 4th gen 10 bolts are stronger than what the "weak 10 bolt reputation" is.

 

9bolt.com only sells replacement stock parts.

 

I wouldn't go nearly that far. A factory 9" is much stronger than a 9 bolt. A 9" and a 12 bolt have similar strength. Maybe closer in strength to the Ford 8". (not the 8.8)

A 9 bolt is stronger than a 7.5" 10 bolt for a couple of reasons. It has a larger 7-3/4" ring gear. It uses a 4 spider carrier. That isn't a big improvement over the 10 bolt but it does make it stronger.