I'm thinking of selling my 10year old 2GM20F with 1300hrs but don't know how much to ask for. Any idea? Planning to get a new 3YM30 for my h326.
A completely rebuilt engine is around $5,000. That includes everything, i.e. tranny, alternator, starter, panel and heat exchanger. As Steve says, the GM series is no longer made and the new ones still hanging around in distributors' warehouses go between 5 & $7,000. So my guess is if you could get between 2500 and 3000 you would be doing good. You probably will need to change the prop and maybe the shaft and coupling to accomodate the new engine, so you could throw that in and get the $3500 you had in mind.
Do not forget that you will need to reconfigure your engine room a little bit for exhaust hose and control cables because the YM series has the heat exchanger and cabless on the port side of the boat, opposite of the GM series which is on starboard side. You are right that the YM is real smooth. Good luck