My '77, L82, 4-speed has a 3.70 rear end.  Chevy did this to give the car some added response.  However, this means that the car is a real gas hog.  At 60 MPH the tach is at about 3500 RPMs.  Am thinking about getting the rear end changed to a 3.53 to get the revs down and thus save on fuel.  It's a big job and won't be cheap, but the car should handle OK.  The only downside is that I will be changing the car, which is totally original with only 30000 true miles. Any thoughts on this?

I changed my 1978 L-82 automatic from the factory 355:1 to 308:1 gears a couple of years ago for the same reason. I definitly lost some kick out of the hole but gained some top end.

Dave is right about the minor change that you would see. If you do change you need to go with the 308:1. But the overdrive transmission is really a better approach.
ps: I like your cat.......take care,
Larry

Dan
Welcome aboard! I went the other way for gearing but I will be driving mine very little. With the 4 speed trans Im not sure what pulling out would be like if you went to 3:08 gears ecspecially if you are on a steep hill.   The others are correct when they say going to 3:55 gears may not yield much of a change  Is this your daily drive? Also as said in the other posts you will need to change the gear in the trans if you want the speedo to be correct. Going from 3:73 to 3:55 you might not need to worry as its probably only a few MPH difference. Keep us filled in as to what you decide and best of luck in which ever direction you go.
Rodney

Another option might be 3.36 which was standard for an L-48 4 spd in the mid 70's.  It's what mine has and I feel like it has the right combo of good low end without being too much of a screamer at 70 mph.  (I think it's around 3K at 70 or thereabouts)

Going from 3.70 to 3.53 is not much of a diff. It would result in going from 3500 rpm to 3358 rpm. I don't think the sayings on fuel would justify the cost of changing the rear.

|UPDATED|8/20/2012 5:09:50 AM (AZT)|/UPDATED|

Thanks for the feedback to all.  Sounds like the 5 speed tranny is the best option, but I know that's not a cheap conversion.  I agree that the slight change to a 3.55 would not gain me much.  I like the compromise--3.36.  Also, there were two different transmissions, I believe, a 2.64:1 and a 2.43:1.  I must have the 2.64.  I think that that means that the first gear is 2.64:1?

Imma gunna throw in with the 3.36 guys too....good all-around ratio. Not too steep, not too lazy. Your L-82 should have the close ratio trans with the higher(lower numerically) 1st gear ratio. It could have been ordered either way. The L-48 engine had the "better" 1st gear ratio transmissions(wide ratio), believe it or not.

Welcome to the gang, Dan!  Anybody with the name "dapperdan" is ok in my book cause that was my nick name in High School (Many moons ago!!).  I have no expertise on this topic but just wanted to say "Howdy" to you!!

I went from a 4.11 to a 3.08 in my LT-1.  Huge change in rpms and mpg.  In retrospect, I wish I had put in a 3.36.  The 3.08
kinda bogs a little with my LT-1.  My 78 L82 had a 3.08 but I think it had a little more low end torque that the LT-1.