If I want to convert my front drum brakes over to disc brakes what year chevy can I get parts from. I am looking for a simple bolt on.

The simplist conversion would be disc brakes off a 1969-1972 GM A-body (Mid-size: Chevelle, LeMans/GTO, Cutlass, Skylark...).

Use the disc brake donor spindles, Master cylinder and prop valve, etc. You will have to modify the brake lines because the GM disc (and all 67 and later GMs ) use the dual reservoir for separate front and rear systems...

But these parts are getting harder to find used...