Anyone out there change out their existing 2.72 diff with any of the above diff and how do you like the change?

I had the 2.72:1 and went to 3.55:1 gears. big difference in acceleration.

I went to 3.70 for perfomance.

What r the costs of changing the gear ratio in a vette. Can you just change an already loaded rear or do you have to have someone change the ring and pinion. 

If you're going to rebuild it anyway there is no difference in cost. And if you want to change ratios you might as well rebuild it, it needs to be torn down one way or the other.

I have an OD tranny with the 3.55 in another car and do well gas mileage wise.

It should be alright. You could go with 3.30:1 gears also. I asume the 4th gear is 1:1 on the new trans. 3.70:1 rear would not be good for highway driving.

I really think it depends on what you plan on doing with the car. A lot of highway I would go 3.08, as long as you have the horspower to back it up. Our '71 stroker, auto has a 3.08, and its fine..GREAT on the highway. I have 3.36 gears in the Vert, not much freeway, around town is nice. 3.70 in the LT-1, its a MONSTER off the line, but runs about 3000rpm at about 60MPH. The freeways here are 75 MPH, so not much freeway for that car.

My '74 has 3:36 rear gears, and a 4 speed. It tachs out around 3000rpm @ 70mph.
Going from a 2:72 to a 3:07 isn't gonna be a big difference, but it will be a little more "peppy". The 3:55 will be a lot more "peppy", but it's gonna wind the engine up a lot tighter(at hiway speeds) than what you have now, for sure.
Any change in rear gear ratios will also require a change in speedo gearing, if you want the speedo to read correctly.
I would stay with the 3:08, or maybe the 3:55...but no more, unless you rarely go on the road with it. High rpms get to be annoying after a while...

[QUOTE=rod7515]
What r the costs of changing the gear ratio in a vette. Can you just change an already loaded rear or do you have to have someone change the ring and pinion. [/QUOTE]

If you have a diff assy that is already built/loaded, it's a simple(somewhat) swap...take the old one out, put the new one in. If you want to change the ratio of the diff you have, then it needs to be dis-assembled, and rebuilt with whatever gear ratio you want, that will fit in the carrier. The stock carrier will only allow you to go to a certain ratio before having to change the carrier. For instance, you couldn't install a 4:11 gear set in a diff that has a 2:72 in it now. The carriers are different. The carrier is the part that the ring gear actually bolts to. The lower(higher numerically) the ratio, the thicker the gears are, which requires the carrier to be different.

The cost to replace the diff assy with another one would be about the same as having your's built with a different ratio. Prices are different all over the country, so it's hard to put a price on it. Check with a local Corvette shop, or differential shop, for an idea of the costs.
A normal "rebuild" of the diff shouldn't be more than $250(labor) or so, if you take it out yourself. If a shop does the entire job, you could be looking at $1500 or more...

I went to 3.70s.  It will yank you out of bed. is also a screamer of 60 MPH on longer drives - not too many of those...