Where is the reverse transmission located?

What is your question?

When 1st start up, could hear winding noise. After the van is warmed up (10-15 minutes), put it in reverse and would not back up. Had to push the van to back out of the parking lot, driveway

What makes this problem better or worse?

It worsen when it's in gear and the hard jerk

How long has your 1995 GMC G2500 had this problem?

8 months