What outdrive do i have the boat and motor is a 1990 glastron 19.5' with a volvo penta 230a. On the side of the outdrive it says SP Cd Trim On the back of the outdrive it says Volvo not being stupid here but a buddy says it was an OMC Outdrive so i just wanna be sure. Here are a few Pics..... Any help on maintenance or tips would be great thanks.