Online Marine Diesel Engine marketplace

Where are you located, what do you have now, and how much hp are you looking for?

You should call the local cummins/cat dealer and tell them what you're looking for, your budget, what you currently have, etc. They'll be able to help you out.

If you're looking for brand new, let me know what you have and where you are.

I can point you in the right direction but I need to know where in the country you are. The local marine diesel dealer network is where you'll find something.

You're going to have to make phone calls and go put your own eyes on stuff. Its a niche market, and you're not likely to find what you want posted on the internet. You might find something, but it'll almost definitely be an overpriced busted piece of shite if it's even real. Pulling good engines isn't a whole lot of a thing. There's not an abundance of used QSM11's or marine 8v71's in good shape laying around.

The dealers will know who's thinking about repowering if they knew they had a buyer for their current engines, etc. Put the bug in their ear and they'll find you something. They want to sell guys new engines and will try to find someone to buy their current pair.

Cat, Cummings, mercury Marine (Volkswagen TDI) and Volvo are the most common from what I remember.

You might can find a rebuilt Detroit diesel

Call Fisherman's wholesale and let them know what you have, what you're looking for etc. It might take some time, but he'll find you someone about ready for a repower. Also call Johnson's diesel in Mississippi and Tony's Marine in Destin.

Those guys are all very well connected with the local fleets of charter boats and commercial guys. If they can't help you, you can't be helped. Its peak fishing season right now so if you need it quick you're screwed, but if you have time you'll have some options.