Had a customer buy a boat from auction. It is twin engine vee drive, Mercruiser 350's. Port engine is there, standard LH rotation. Starboard engine is gone, trans/vee drive still there, but nothing else on starboard side for the engine. Boat is late 90's early 2000's. H.I.N. is covered by swim platform. My question, since I need to replace the starboard engine, will it be LH or RH rotation. I'm thinking standard/LH rotation, reverse rotation done through trans/vee drive, but not sure. Both trans/vee drives have exact same numbers, no indication of LH or RH rotation. Any thoughts ? Just found hull number, 2000 model Sea Ray Sundancer 310.

It will be a RH motor. Merc trans (more then likely a B/W trans) can spin both ways (by flipping the pump over 180 degrees) but it has a forward and reverse gear and can not be run in reverse for long. No matter what though a B/W trans can not change the direction of the rotation by it's self.

That is correct unless it is a 5000 series or a Hurth/ZF. I don't remember when the switch was made.

What is the model number on the transmissions? Or the existing engine serial number?

No numbers on the existing engine. Tranny/vee drives are Velvet Drive 5000 series which are reversible. Both trannies have the exact same numbers 20-02-003. So.. I'm guessing both engines will be LH rotation with starboard tranny reversed. What do y'all think ? Port prop is LH, stbd prop is RH.

I have a friend with a late 90's 300 sea ray 350's V-Drive and the port engine is a RH reverse rotation engine, is the starter still on bell housing ? if so power it up and see which way it spins

Port engine is definitely LH, standard rotation. I had already pulled the starter and was able to get it to turn enough to tell engine rotation, assuming starter was correct.

5000 Series ONLY works with standard LH engine rotation. With these transmissions the prop rotation is changed in the the trans.

71/72 series requires opposite rotation engine.

Yes sir. I made note of that a couple of posts up. Thanks.