Just spent over an hour getting the round spring retaining clip on a new rear wheel cylinder on my 87. The wheel cylinder is tight against the backing plate but it is loose and I can twist it. Is this ok? A guy I work with said as long as the clip is holding it flush to the plate its ok. I see that the ears at the top of it cant let it turn but so much. Maybe a dumb question but I had to ask :?

perfectly normal, I thought the same thing myself, horrible design on GM's part, so much a PITA next time a wheel cylinder needs replacing I will take it to a brake shop.
I can't remember and I did a search on here, maybe was another GM forum but I belive you can change out the backing plate from an earlier style and use the wheel cylinder that is held in place by a nut- much easier/quicker to change them out!!

I think Ill do that next time too..I did get a tip today from a guy at our local NAPA store, he said that some new wheel cylinders are machined so that one clip ear isnt as deeply notched as the other, and makes getting the clip on alot easier. Anyway, like you said they are a PITA to change :x

Here's a good tip for getting those clips in. First wedge a large chisel or block of wood between the wheel cylinder and axle flange. The will hold the WC tight against the backing plate.
Next get a 1 1/8" thin wall socket. Craftsman 12 point chrome 3/4 drive works the best. This socket will fit right in the back over the clips as long as the rust build up is not too bad. Tap the socket with a hammer until the clips completely seats.
Now if the clip is on there and doesn't seem to be completely seated on one side, simply place a screwdriver against the non-seated side and tap with a hammer to seat.
Remember the real trick here is to have that WC wedged tight against the backing plate. Makes all the diference.
Mike

A large 'c' clamp along with the thin wall socket works good too. Rick