drive shaft info

[easyrider]

I'm progressing slowly but surely with this truck. I am now putting the transmission to engine and into truck. My question is: Is the spline in the automatic transmission the same as the one that is in the 3ott transmission that was in the truck originally? Will I have to replace the yoke on the drive shaft to make it work? And, will the drive shaft fit length wise? Is the engine/3ott drive shaft length the same as the engine/auto that I am installing?? Lots to figure out and the best way to do that is ask someone who had done this before. You guys are an encyclopedia of knowledge and with the years of experience you have, I trust your lead. Thanks in advance for all your help and advice.