im doing this on my truck now, its a peice of cake. you do need to weld aluminum, the shift fork rod is in a different location on the dodge, so a bung has to be welded on the dodge case to match the chevy front half. other than that its a bolt together deal, unless you want to raise the fill plug and add the support brace treaded part on the front output side, then more aluminum welding is required.
as far as changing the shaft, once you get the back cover off, you pull the snap ring off the front output that holds the gear on, then pull the chain off and you can lift the entire output shaft out and drop the dodge output in.
im going to do a write up when i get mine done, which hopefully is within the next 2 weeks. just waiting on the aluminum wire and sleeve.