Yes on your set up, the drum uses the same brake shoe as the parking brake. I'm not sure what is causing this for you, but I'd have to say its something in side the drum. In my 89 I had the innards from the drum fall apart, wasn't good.

 

Hmmm... I remember when I was about to give up on moving it, I pushed the parking brake lever down while holding the release and pumped it a couple times and noticed it felt like something was loosening up, the lever didn't go down far the first time but after each time i pushed it down it went down farther to where it would be "normally"

... after that I put it in drive and after a few seconds it unlocked and i was able to drive forward... always locks up in reverse though, I went REAL slow and it didn't seem to do it as quickly... ugh gotta love cars

 

Did you pull the drum off and check the brakes? It sounds like maybe you have a damaged shoe hanging up in reverse. The automatic adjusters also work while in reverse and brakeing.

 

Hi K1500Sport,

Welcome to the Chevy Forums.

I had a work vehicle a while back that got the axle twisted a little, so the brake backing plate was rotated @30 degrees, it needed new brakes every year. At some point you will want to pull both rear wheels(at this point, new brake shoes,hardware, and drum refinishing may be in order, anyways) and check carefully to see if the brake backing plates are in the same "clock" position on the axle. If not, for some reason, this accelerates brake wear.

Plowing snow usually tends to accelerate drive train wear and tear also. You may want to plan on having an alternate vehicle to go to when your alpha plow hits a snag.