IIRC, all 1986/1987 naturally aspirated Buick 3.8l motors are 109 blocks like what came in the T-types. Oldsmobile, Buick, whatever came stock with a Buick 3.8 in '86/'87. Check the casting number if you can find it, if it ends in 109, you're golden. The NA blocks don't have the oil drain hole...