im going to be doing a 350 swap on my car and im thinking about swapping the peg leg rear out of my car for a posi unit for 3.73 gears or atleast 3.43 posi. but i cam acrossed a 2.77 posi series 2 rear end for a decent price, is it worth the swap? or am i better with my peg leg?

 

I went to a 3.42 with a 28 spline Eaton Posi. from a 2.73 open differential with my 10 bolt and it is the single most important upgrade IMO that can be done other than a engine upgrade Get the 3.73 or 3.42s with a posi and you will be soooo happy.Get away from the 2.73 highway gears especially with the 700r4 with OD. a posi in a 2.73 is still going to su-k. IMO

 

3.43 up to 2.77.....Depends on what your goals for the car is & usage of the car.

2.77 will do better for mpg on the highway at cruise, but likely will get worse mpg if you do a lot of stop & go stop light driving.

 

2.8 won't pull a 2.77 in OD. 350 depends on the build. If you want 30 MPG, then the 2.77:1 can be useful, with a mild-enough cam. But to make it perform, you'll need to add a turbo. Posi by itself isn't worth such a swap, and that one may be very worn. Finding a rear with the correct ratio, and posi, is a long shot, unless you settle for a wider 4th-gen rear. Even then, 3.73:1 wasn't factory-offered.

 

What rear end do you have? if its a 10 bolt its 2.73's, 3.42s and 3.73's.

If its a 9 bolt aussie rear, then its 2.77's, 3.45's, and 3.70's.

If you found a 2.77 gear/posi setup, chances are its a 9 bolt and wont work with a 10 bolt if you have 3.23s as listed in your profile. Also need to note what year 10 bolt as early ones have 26 spline axles while later ones got 28!

The swap can be worth it..i know my L98 responded nicely from 2.77's to 3.27's and then switching 9 bolt rear for a 10 bolt and 3.42 gears.

My 99 LS1 car however didnt gain much with 2.73's going to 3.73's. Just lost a good bit of mileage and only gained a tenth at the 1/4 mile....only .05 in the 60 ft.... Not worth the swap money, I'd have soon just kept the 2.73's.... I may throw a 2.73 rear back in it.

Both have torque converters...2800 in the old L98 car, 3200 in the LS. IMO, the converter makes up a good bit for lack of gearing. My cars responded well with just converter swaps on highway gears.