2000 ram 1500 5.9 reverse

I have a ram 1500 5.9 i just had the trans rebuilt got it all in the truck put fluids in it and it shifts perfect in all forward gears but when u put it in reverse it does not move does anybody have any ideas on what the problem could be.

your low/reverse band is probably out of adjustment. You'll need to drop the trans oil pan and adjust it. I would seriously go back to the tranny shop that rebuilt it and have them check the low/reverse band. Hopefully, when they put it all together, they didn't overtighten the band and break it.

Is the adjustment underneath the valve body

Take it back