Ok, the Vehicle is a 1999 Chevy 3500 HD. I'm pretty sure it's the 4L80E but not positive. Anywho, lost reverse, all the forward gears are fine, fluid is normal, not foamed or burned. I know the shifter is going to the reverse position correctly as the reverse lights come on. I'm thinking a possible broken band in the tranny, but transmissions aren't really my thing. Any ideas?