My 07 320, Mercruiser 5.7L 350, has identical engines, and the transmissions handle the counter rotation. The parts manual for your engines based on serial number would call out any differences.

 

The source for counter rotating engines died when GM stopped making counter rotating 7.4L v-8's.

Diesel boats suffer from the same limitation so counter rotation is only achieved on later model boats by running one transmission in reverse and the other in forward.

Check your preferred vender to be sure by verifying that he only offers one SKU for your engine/year application.

 

Thanks guys. I'll verify before ordering but it sounds likely that they'll be identical.

 

They were identical on my 2000 380.

During the survey, the starboard failed, the shop pulled the port and finished the test, then ordered a new one

 

Great. I placed the order.

BTW, it's harder finding the OEM ones. There are TONS of cheap knock-offs but I wanted to avoid those.