what did you pay to hook the 300 to the tranny? someone told me it's like $500 or so. after hearing that i started thinking tera 3.15:1 and 5.13's for a 40:1 final with 36's. or 300 and 5.38's for about 35:1. i found reman 300's all day for $400 at the jeep yard by my house. the parts chick made it sound like they have a bunch of them. if i get the 300, i can probably sell my 20 and be a little ahead on the deal but not sure if the final ratio will be low enough. oh well, at least i'm narrowing it down. i found a rear end too. $200. sweet! <img src="/forums/images/graemlins/cheers.gif" alt="" />
the link says the th400 has a 2.48:1 1st. if it's the same in a chevy as jeep(which i don't know why it wouldn't be) you would have a 33:1 final.

http://www.jeeptech.com/wiki/index.php/Transmission/Factory/TH400