4l60e and no reverse

Finished my swap today and started up the truck and let it warm up it cranked on first try with no problems and no leaks after letting it run and warm up while I was checking everything I got in and pressed the brake and put it in drive and nothing happened went throughout all the gears and nothing shut the motor off and checked the trans fluid it was pretty hot by then and it never even registered on the dipstick ran to the partsatore and got some ATF for it put three and a half quarts before it would register a little over the cold mark well I got in it and cranked it up and let it warm up again and went to put it in reverse and nothing so I said maybe it's low still went to drive and it down shifted and felt te truck jerk a little let off the brakes and it went On it's own in all gears but reverse. Been doing some research and looms like the sun shell and sun gear is toast can anyone give there input

How long did it run with fluid that low?

5 minutes max

you have every gear but reverse?

Every gear but reverse is correct

hmmm, thats some crazy shiz, maybe nathan will chime in.

I have the same issue, but I did a rebuild on mine with the swap and now I have forward gears and no reverse. I was hopin to find some ideas on whats goin on in there. Hooked up tech2 TR shows reverse for PRND321 but not for the TFP. Did anyone figure this out?