Hey guys, I need some help diagnosing a problem. Today I parked the blazer on a steep(30 degree) incline on our loading dock. When I let off the brake to get out, the truck started rolling forward, making a loud kachunk, kachunk, kachunk. It rolled about a foot like this until i applied the brake again. After I let off this time it held. It sounded like the noise was coming from the rear axle area. I don't know much about axles, but the only thing I can think of would be the ring and pinion gears slipping. Any other thoughts? or ideas how I should go about troubleshooting this?