Cant say if it makes a difference, never tried modifying thr merc ones. But, the merc bellhousings cooler deals have been around since the days of the old 370 and 400hp 454 engines, which were not quite 6000rpm , monsters lol.

If they were used on 900SC's it would seem like they'd be adequate for all but the most extreme applications. Unless their was some mod done for the later engine packages.

Personally I would rather have more cooler then needed and run an oil thermostat then not have enough of a cooler. Especially if you run hard.

Check out Mr. Cool, Russ has taken great care of us. Took his family for a ride in unleashed this summer to thank him. They offer tube and plate style, if you don't see what you're looking for call. http://www.mrcool.us/hi-performance-coolers.html

Offshore your point is well taken. At this point it seems like it's not completely out of the question to use one 8 plate in my situation, after all for 20 years the boat has relied on (1) 2" x 19" cooler without issue. I have ordered t-stats. There are a lot more used dual cooler set ups available with 8 plate coolers than anything else so I'm going to try it. I believe it'll get me too and from initially, if an upgrade is needed it sounds like a 13 would certainly suffice and I still have the other side for the the transmission. Mr Cool has plenty of cooler options, too bad he doesn't sell new bell housings....

One 8 plate should be more than sufficient. We hand to restrick the water flow to get any water temp.

Thanks

Be careful when buying used oil coolers, very hard to flush all the metal out if there was engine problems or neglect.

i will go a little farther,don,t buy,don,t even take if free used oil coolers.buy new,a lot of fresh engines have been ruined from crapped up oil coolers.same goes for trans coolers.

Good point on the use coolers, thanks