There are 8, 4 each side.
If you have no rust issues they are not a real bad job, but its some work
Rattling body, doors not lining up, body lean on the frame, all those indicate compressed mounts. Yours is an 81 so they are compressed, count on it.
Replacing them I would go with Urethane, last time you will ever replace them. Its just there to isolate the body from some frame vibration, so anything other than solid mounts will work. I like the urethane because its more stabil than rubber.
The passenger side is pretty easy, loosen all 8, then use a floor jack with a piece of wood to lift the body a couple inches off the frame and replace the mounts. Clean and paint the metal under the mount cussions whilt its off of them. be sure and get the shims back in the same locations.
The drivers side takes a little more work, you will need to disconnect the rag joint for the steering and the brake lines going to the MC.
Tanke a look at the #2 mounts before doing anything else, see what they look like, this could be a bag of snakes.