What years would I be looking for to find one of these. It's either find one of these, or stick with whatever 4 bolt 2 piece main block the machine shop can find to replace mine. Not familiar hardly at all with the later motors, but realize I'd need a matching crank and flywheel to retrofit to my SM465. Want a 4 bolt because, hey, thats what they ruined. Is the flywheel I'm gonna need going to be one that was originally mated up to an NV4500? (I've got the "big" clutch now obviously) Anyone know if the cars got 4 bolt main motors after the changeover to one piece rear mains in '87? Just need some places to look locally, if I can find a motor that meets my criteria, it will save me about $400 on retrofit roller lifters.