will an early 84 5 speed go into a 81 5 speed 4x4 without problem or am I gunna run into lengh issues. like cross memeber and drivelines?

I've tried to search for my questions but only found stuff from 85 and up nothing pre 84.

 

L Series transmission in 1st Gen trucks are about 20 3/4" long, all later model transmission are 25'ish "long, you will need to move the crossmember, lengthen front DS and shorten rear DS....

 

Thank you that is what I thought I heard a long time ago but just couldn't find the info on it..

thanks again for your time