small to big block question

[otsenre]

I am converting from small block to big block and to a 400 tranny. Originally had a 307/powerglide. The big block I am going to use was in a 1 ton C30, I know I will need to find another driveshaft, or can this one be made to work. Also, will the rear end I have on here support the big block and tranny, it is a 5 lug coil spring, Thanks in advance

[Hart_Rod]

I'm pretty sure you're going to have to change the drive shaft because the powerglide is shorter than the TH400. As far as the rearend, it all depends on the gears, posi or non posi and how much you . Good luck with the install.

[chevy72blu]

Hart_rod is right on. Dont forget you will also need new motor mounts/towers (some years can be converted from others). What year is your truck?

A stock TH400 will do fine with a stock BBC. What rear is in the truck? 12 bolt? 10 bolt?

[70rs/ss]

If it's a 12 bolt they came behind, SBC and BBC so it'll hold. The drive shaft may not fit, but that is trial and error there. Put the BBC as far forward as it will go so the valve covers and the distributor clear the firewall, this will also requite a longer shaft, you can install it and measure, then hit the wrecking yards to see it you find something, or a new shaft will run about $150. Find a newer one piece long shaft and have it cut down, good luck I have put about 5 or 6 BBC in short beds and they are a riot!