[77chevy400]

Hey guys, i got a couple of questions. I have a 1977 chevy pickup, 4x4, lifted with 37" tires. I recently purchased a 383 stroker which i will be dropping in as soon as my Weiand 6-71 supercharger comes in and is installed also. I also will be purchasing a new tranny set up to handle all this horsepower but my question is....should i get the TH350 or TH400?? Also the motor dynoed at around 445 horsepower so i dont know how much more horses the Weiand supercharger is going to kick out. But with all of these factors in mind (383 stroker, race tranny, supercharger, 37" tires, what gears should i go with??? I currently have the GM 12bolt in the rear and 10bolt in the front. Does anyone know the factory gearing for my year? Also i have heard of a lot of street guys going with the Ford 9" rearend in their cars. What would be a good gearing or maybe even a new rearend completely with all the factors listed above? Keep in mind that it is a 4x4 with 37" tires and i will be using this truck for mashing in the sand dunes alot. Thanks guys!

[DoubleVision]

for what you plan to do, i would use a TH400. as for gears, the automatic tranny 4X4`s mostly came with 3.08`s, but you could get the code off your rear and get a haynes manual for that year truck and it`ll give the ratio, or you could remove the rear cover, stamped on the ring gear will be 2 numbers, it may look like this 41 11 divide them and you got your ratio. as far as the 383 goes, if it made over 400 horses, I`m assuming it has over 9:1 compression, if you plan to run the blower you`ll have to underdrive it to use it with that compression ratio. you may also want to have a heavy duty sprag assembly added to the tranny as it`s the weak link in both the 350 and 400 tranny`s. if it were me I would go with 3.73`s or 4.11 gears. but if it already has 3.42`s, and when the trucks in low range with the power you plan to make, it would work fine.