I recently changed the rear coil springs. there were no rubber isolators on the springs I removed. are there supposed to be rubber isolators on top of the rear springs like there are on the front? the manual doesn't mention them like it does for the front.

 

Yes

 

if you cant find isolators for sale, you can use a piece of rubber heater/cooling hose that you just slide over the coil. i used about 12" of hose (maybe 5/8" diameter?) and pushed it down so it covered about a full coil. then secured it with a hose clamp.
note- doing this will cause your cars rear ride height to drop about 1/2" ..however in your case, if you had NO isolators, you will probably go up higher in ride height. the isolators will add about 1" of so of ride height

 

Only the front have 'em...

 

Front and rear have them. The rears have a couple different thicknesses IIRC.

 

Yes the rears have isolators. Looks like item #9 in the diagram you posted. Some people, such as myself, use rear isolators from the 4th gens. They're about 3/4" thicker than those on thirdgens.

 

Use heater hose and run it through the first coil

 

That's how I fixed the rear springs from the lowering kit. Made the car sit lower in the rear and the 4th gen parts put it back up in a perfect spot.

 

Same here. After installing the springs, car sat perfectly level with no fore/aft rake at all. With the lines of the car it just did not look right. Put 4th gen isolators on and it sits much nicer.