It would be easiest to look for rear wheel drive 3.8 equipped Cutlasses, Regals, or any G-Bodies. 1986 and 1987 will have the 109 block but the other 3.8 blocks will be fine for a street car too. This is just for the block; if you need a crank and rods you'll have to find a 4.1 out of a big GM car from 81-84 I believe. They'll have the crank and rods but you could use the bigger block as well. GNTTYPE.ORG has all of this info plus pictures and casting numbers.