2003 trailblazer gear lube coming out of transmission breather rubber tube no reverse
 

Newbie looking for some direction, unit will shift into reverse but will not move, its like the gears aren't engaging (can hear a slight clunk when giving it gas)but will work in forward with no issues. Any ideas or suggestions? Thanks

Is there any kind of grinding or any unusual noises other than the clunk?

Had the same year model and did the same thing. You're going to have to split the case and check the fork. I took mine to a dealer. They couldn't get the part in before I was going on a trip, so the mechanic (OPT) did something to make it work. No guarantee, but it worked for years. So long ago I can't remember what it was that he did.