take my cars to a Dealer for work. New shocks on my 1982 280ZX: I pull out of the lot and hear the 5 speed transmission making continuous dry bearing noise after they do the work...ended up needed new tranny bearings a month later ($1,000.!). I had copied the FSM procedures for shock replacement for the mechanic...and found the papers crumbled into a ball in the hatch area...I think the mechanic took the car out and beat the hell out of it on a test drive. I have other horror stories too.