I'm going to do a gear swap in my hot rod truck,it's a '76 Chevy stepside with a warmed over smallblock(9.5:1,224/230@.050,Vortec heads,single plane),700R4 and the rear tires are 31" tall.At first I was considering 3.73s,then it was suggested that a 4.10/4.11 may be better with the taller tires.I know either will make the deep first geat even deeper,I'm kind of thinking of the final drive ratio,it has 3.08s in it now and it is very inefficient in o.d.,it seems to lug it down some.I also haven't hooked up the lock up yet for the converter,going to switch to a 2400+/- converter and hook up the lock up at the same time.

I'd like to see what you guys are running and comment on the performance,please.I may have asked before,can't remember,but I'm getting around to doing it now/very soon.

thanks

With that tall of a tire I would go 4.10's if it was me. The 31" tire is very tall. If you want to use lock-up go 4.10's. You could get by with 3.73 only if it locked-up at 60 mph or above. At 2000 rpm you would be at 65 mph with 4.10's and 70 with 3.73's. The cam you have along with a single plan intake would probably work better with 4.10's.

You need to hook up the lock up converter. The converter is still slipping while you are driving, which means that you are making a lot of heat in the fluid. This will cause transmission failure.

The 4.10 will probably be good. I have a 4.11 in my Camaro with 32 inch tires and no overdrive. It runs about 3200 at 70 MPH, I think. It's been over 3 1/2 years since I drove it last.

You need to hook up the lock up converter. The converter is still slipping while you are driving, which means that you are making a lot of heat in the fluid. This will cause transmission failure.

It's not being driven much for that very reason.It has an auxillary cooler but I really don't want to chance it.

That is where I was leaning towards on my gear selection.The 2 people I know using 700s use a 3.73 w/a 28" and a 4.56 w/30" tire.

Thanks for the input.