I have a 1993 Mariah 21' Shaba with a 350 ci 4 barrel. I got it out od the barn yesterday and changed the oil and lower unit lube. I used the ($15/qt) Mercruser "performance" lube. I started it on the muffs, checked for leaks, and shifted it into reverse and into forward gears. All was well. I took it to the river, backed it off the trailer, put it in forward and it died. I removed the lower shift cable to try to put it in gear. I could shift it into reverse with two fingers but not into forward no matter what I try! I assume this indicates a problem in the gear box?!?! Did it break on the trailer? Which generation lower unit is on my boat?