Sy-1177 said:That is the same casting # i have on mine! Those are supposed to be good flowing and heavy duty heads. I heard from a guy that the casting # for the heads specify that they were made by Yamaha. Weather or not that is true is questionable? Just out of curiousity i pulled a couple more #'s off if anyone can define them. On block: 177N18; 4.3LG; 10066011. It also has purple markings on crank and pink markings on push rods. Heavy duty right? I had the #'s for the crank but i lost it and the oil pan is on right now so i'll have to get that later. But the block is supposed to be an 87-88 because it has the hook up for a manual oil pump on the side. Sound right? Also it is supposed to be oddfire (I think). Any response would greatly help. Can I use this motor for the Sy?
262/4.3L GM 1986-92 1 pc. seal W/O balance shaft, center mount valve cover, roller tappets Est. HP 175-205 14093683 10105867 10066011