You'll need a different/modified cross member, a new driveshaft, yoke spacer, a manual speedo T56 or speedcal and of course a new shifter.
I've done this swap a few times and it's pretty easy. There are two major benefits to the T56, the removable bell housing makes pulling the trans a snap and to rebuild the T56 is the easier than the T45/3650's. If you choose to stay with the standard 10 spline and not upgrade, it's a cheap and easy upgrade if it ever does break. It's the main shaft that normally is the culprit when they have any failures.
You can buy all the parts on ebay for about $2500 for a standard trans. If you do buy the upgraded trans, only buy from Liberty gear or D&D. Liberty actually is the company that builds a lot of the A/M transmissions that are sold.