Getting ready to install 572 CI 700 HP ...700 TQ engines in boat.... Need couplers and Im getting mixed stories about which couplers to use. Some say aluminum some say steel. Any feedback or advice would help. Thanks in advance....

lets see how close my text was to actual answers lol, you buy first round if its word for word lol

If it has a spline better go with steel aluminum will wear out.

No question steel, buy the 575 sc steel couplers with long snouts, I have been running the same one approaching 400 hours behind 750-1115 hp in my Baja and it still looks close to new. My original aluminum one on the other hand, the splines were 1/2 gone after running 650-750 hp for around 100 hours, Smitty

My 700HP, 575SCi aluminum couplers look new at 320 hours.
Well, until the drive locked up on the forward engine. The drive input splines were twisted and the stubshaft that goes into the coupler was in 3 pieces. The splines were still fine but the hub wasn't straight anymore.
So much for a "weak link".

Never seen a 575 sci "aluminum" coupler as the ones everyone buys that are heavy duty ARE the 575 sci long snout steel couplers, were yours originally aluminum or something you put on your boat? I see on your info your boat was a 2002? Looking thru some stuff it seems they upgraded the couplers at one point for the 575's around 03-04, maybe makes sense why yours were aluminum.

i never knew thet had still couplers, hell i ran alum ones on my 42 with blown 557s never had a issue, i guesss i had it set up good.

Can you get the steel splines with a short snout? My engine fits so snug that i don't think I can install it with the long coupler.

They only used them on the 575SCI's for a couple years. They were originally made for diesel applications.

You can get steel couplers with the long snout or no snout at all.

So really the difference is, the aluminum wears out faster than the steel? Any other issues that I should be concerned with?