I tried it out and 1 & 2nd seem OK, But when it shifts into D nothing. just slips.
Oil smells burnt and I think it is toast, But have never seen one go in just Drive.
I’m doubtful about it being a modulator, given the other items noted, but will admit that GM shushboxes aren’t my strong suit. I’m going to say the drive band is toast, and if you’re extremely lucky, that’s all.
That being said, tearing it down to replace just that part is foolish, so you’re looking at an overhaul, anyway. Before Rick and Gary T come in and ask the question, how many miles on it?
If this transmission has seen the average level of maintenance that people give to their transmissions, it’s gone 17 years on the original fluid and filter and is a goner.