1999 Chevy Silverado 1500 - 4L60E won't go past neutral, wheels don't move

[Xavier]

I recently picked up a mechanics special truck for the winter, I was told it needed a torque converter but the guy had one he'd send with it, he just had other projects he'd rather work on.

My father has been a mechanic for 30 some years and owes me some money so he agreed to "work some off" by getting this truck moving. He admittedly isn't a transmission guy, though. He was able to swap converters in the transmission but the truck still doesn't move.

Currently you can physically "shift" to every position but the dash only goes to R or sometimes N. D123 never light up. Revs drop when shifted into R and come back up when shifted into N. There is no change in D123.

Any transmission guys got some clue to where we should be looking?