94 GC auto V8, first off it started shifting hard and noisy into 4th, now it barely moves in reverse. Is it the tranny for sure or is there something else I can check. Fluid is full, a little burnt smell but the color is good.

If the tranny has a burnt smell, it could be overheating, which could cause trouble shifting. I've heard good things about Lucas transmission treatment. You might want to try that and see if it makes a difference in improving the shifting.

I'm not a transmission expert; my other recommendation is to take it to a reputable transmission shop and have them test drive it. Let us know what you find out.