Just replaced the fuel pump on my '03 Tahoe. The thing is in the tank and the local shops wanted around eight bills to do the job. Took me two days, one to drop the tank, one to put it back in, real PIA job. Don't know if I would want to take on a tranny job at my age it, gets hard to bend over and scoot under the truck after a few hours. Don't even want to go into chasing falt codes, it needed catalytic converters also which was done at a shop.
Good to hear you got the tranny in and have the old girl running. Love the old Mercedes diesels, they will give you a half million miles or more.