Hi this is my first time on this forum and yes I am not an owner of a cadillac but my Godsister was just given a 86 coupe deville and the vacuum pump needs to be replaced if any one could tell me what site would have information on how to replace the vacuum pump or is it something that can be done with the average tools or do you need any special tools.

It has been a while since I did one of those. There are a couple of bolts that are hard to get at and the adjuster on them are a real pain. Besides, you need to put the vehicle up on a hoist. You don't need any special tools, though a long extension and a 13 mm flex comes in handy.
Check the Library for information on that particular caddy.
Good luck.

FWD it's a bitch. First time I did it it took me a couple of hours to manuver it out.

RWD not sure. but should be easy for a RWD