Rear end gear questions for my old white 69...

[jayharrell]

Well.. my 69 is back on the road after a year. rebuilt the 72 buick 455 with a t400 that was in it. But hitting the road it was running 70 at around 3500 rpm. My rear end is the 3.73. The motor setup came out of a 72 Buick electra that had 2.53 gears in it. I've always thought about a 3.08 posi in it to drop the rmps and get that power planted to ground and boost the current 18mpg to around 20+, but it seems the mpg will still suffer with the 3000 rpm on the drive into work.

Is a gear set up higher then a 3.08 even avalible for this rear end?

Anyone think i would loose that much giddy up by dropping to something higher geared then a 3.08? I'm figuring about 380hp and 400 tourqe currently on the 455 with all the emission stuff striped off, headers into 3 1/4 pipe with some flowmaster knock offs dumped just before the back tires.

The truck will burn both tires to the rims if i let it, but doesn't want to go more then 90mps.

Just venting a thought and looking for some advise.

ttt