my 70 has a 408bbc and an m21 close ratio in front of 3.31 gears. it's been 13.73@104, 2.26 60'. I understand the close ratio tranny and 3.31's dont help each other much. my question is: should I look for a t-10 or an m-20? or should i go with an .... auto? maybe 3.73's out back? the car is mostly a street cruiser, but I wanna pick up performance where I can

Your time is slower than mine and I'm in a Nova with a 355. I would go with the T-10 since the casing is stronger than the m-20 or m-21. Plus the higher first gear will get those 60's lower. I'd get the trans first, then see how it rides. The 3.73's are better for the track but on the highwas, you'll be screaming.

104 MPH with a stick shows 13.3 capability. You run a 13.7. Are you spinning? A 2.26 60' time looks like it. If so, fix that first and you will run better ET's. What exactly is your goal?

IMHO and experience-don't change anything!!
Get some sticky tires (at least drag radials) and improve your 60 ft/launch technique and your ET will dramatically improve.BTW,13.7/104 MPH ain't bad for a heavy Chevelle with mild 3.31's and a 4 speed graemlins/thumbsup.gif

Personally, if you're gonna change anything, I would go with an OD tranny, such as the TKO 5-speed or T-56 6-speed...you have the '4-speed' parts at least, so make it a little easier...it may cost a little more up front, but imagine being able to cruise at higher speeds and/or running a steeper gear (if T-56)...That's just me though; unless it's an original LS6 car or something along those lines, that's what I would do...just seems to make the most sense these days, imo...

well, i suppose i should try runnin on something other than 255 bfg's before I start digging into the drivetrain. when it thaws around here I think i'm gonna get some american racers and see what she'll do. thanks for the advice
-wolf