Sinful 04

C5......... what's the difference between the 1 rib and the 3 rib? When buying used what should I be looking for? Just looking to wake up my stock ride a little and not lose to much gas mileage.

martysauto

1 rib is fine in stock applications. Wheel hop, slics and/or high hp are the most common cause of c5 diff failures.

tblu92

A 3.42 was available on any C5 manual trans--However a 3.42 out of a Z06 is built somewhat stronger--More ribs (not sure guess you checked) But more importantly the gears are "shot peened" If you look at the diff tag or stamp on a 3.42 out of a Z06---It should say " 3.42SP---that's the one you want for strength !!

Sinful 04

Any year better than the rest? I would think the less miles the better. What about a new stall, perhaps it won't matter after all it's still the stock motor. Just trying to wake it up a little. Anything besides 2.73 gears in town should help.

tblu92

I did both to my car--gears and stall----However if I had to only choose 1 that showed the greatest performance gains---I would pick the stall !!!---True 2.73 are awful high I would only change them if you got a deal on a low miles Z06 diff-----A stall is the single best mod you can make on any automatic car !! Engine or trans !!(IMHO) And I wouldn't mess around with a reworked stock diameter unit as they are junk---And get at least a 3000 stall that is aftermarket and made to handle abuse--

PhysicsDude55

I believe 97-01 diffs are "single rib", and 01-04 diffs (don't know when exactly the cutoff is) are "3 rib". Its just more bracing on the case that makes the diff stronger. If you don't do a lot of heavy launches at the track then it doesn't really matter.

Automatic cars had an option for the 3.15 ratio rear end, so that's a good replacement for a 2.73 that still retains really good drivability. All manual C5's, Z06 and non-Z06, have 3.42s, so they're easy to come by. You'll lose some mileage and have higher RPMs while cruising with 3.42s, but a small price to pay for the better performance IMO.

It is my understanding that Z06 differentials have identical cases to non-Z06 C5s that came with a 3-rib diff, but that the gears are shot peened, and stronger.

In GOOD CONDITION, a 3.15 typically sells for ~$300, a 3.42 for ~$500, and Z06 (3.42SP) for ~$700. Your results may vary. Most shops charge $400-500 to replace a differential.

PhysicsDude55

On the left side is a "single rib" differential, and on the right is a "3 rib" differential. The only difference is the case rib on the top that splits in 3 for the 3 rib diff.



Typically in C5's when the differential fails, the case cracks, the internal gears and guts rarely break before the case does, so a reinforced case helps keep the diff together for longer.