I am buying a 2.73 Posi disc rear from my friend for $50. I want to make it a 3.73 posi. Do I only have to change the gears? I am not sure if 3.73's will fit in the 2.73 and I am not exactly sure what I am going to need and what it's going to cost.
thanks!

 

ull prob. have to change the carrier too. the gears will prob. cost around $300 i think and ull prob. need an installation kit that comes w/ new seals,spacers and such for the new gear installation

 

whats wrong w/ your rear now?

 

if its a 9 bolt rear, you'll have to change to a 3 series carrier for about 600 bucks new and then 300 for gears. 2.77's came in the 9 bolt, and since you have 2.73's you have a 10 bolt. stuff will be cheaper!

 

You'll need gears for a 2 series, an shim kit, posi additive, gear oil, I'd change the bearings and axle seals as well.

If you have drums, you'll need a prop valve from a disc car.

It will run you about $450-600 depending on labor price.
We get our gears done for $150.

Gears, $150
Shim Kit, $30 or so
Solid Pinion Spacer, $20, this is highly recommended over a crush collar.
bearings and seals, about $80 or so
Gear oil, $15
Posi Additive $6

Don't know what a prob valve costs, probably $40 or so.