I have installed a 12 bolt posi from a 73 Buick Gransport in my 57 3100. I have the driveshaft from the Buick and I have the driveshaft from my 57. Is it better to use the driveshaft from the 57 which is already matched to the GM truck tranny or do I use the driveshaft from the buick which is mated to the rearend? either way it looks like I have to have something cut and welded somewhere in the process. This is the first time I have ever swapped out a rearend and I dont know what to do.
