my '96 47re did exactly the same thing when it welded a few things together, something with the clutchpacks and a planetary I think. mine finally quit working in reverse as if it was in neutral (but making some bad dragging noises) and in neutral it was like it was half way in gear. then in drive it drove like crap, barely made it to the trans shop.

that was 10k miles after a supposedly good rebuild, a billet converter that the 'local shop' swore was bulletproof. a shop in Yuma AZ was part of the same national trans association and covered it under warranty, fixed a couple things the RIGHT way and I never had a problem after that. the shop that built it the first time said there's no way they would've warrantied it. last time I'll EVER do business with 'Performance Transmission' in visalia.

anyway, get a Goerand Converter and a competent shop and that'll be a great setup! It'll be a few thousand dollars cheaper to get a Goerand than to swap in a stick, I looked into it with my 2nd gen. even an NV4500 will have some things that need to be upgraded, not to mention the cost of finding a donor truck and the time to do it...