1993 Buick Regal Replacing Rear Pads

Brakes problem
1993 Buick Regal 6 cyl Two Wheel Drive Automatic 181K miles

I have attempted to replace the rear pads a couple of times since I bought this car in 1994 and each timie I do I find that the plunger in the caliiper is threaded into the caliper body and cannot be reinstalled after having been unscrewed too far. My question is in which direction do the threads run? Are they reverse threads or are they standard like any nut and bolt combination. I don't want to have to buy another caliper this time just because the plunger cannot be restarted. Please tell me how this is accomplished.

Thanks!

Bruce