To answer your question, no, a gmt-800 box will not work. Different model box, and when I set them side by side, it looked like a different mounting pattern, and I know the putman arm is completely different. So unless you're up to fabbing up new mounts, it's not a bolt in swap.
What I do know is the 94-02 dodge's used the same model box as ours, but with a slower ratio(ours is 15:1 and theres is 18:1). What I have read is it is possible to swap in the box from a 4th gen 03-07 style Dodge into a 94-02 model, so that may be an avenue for a heavier duty steering box. Otherwise sendyour box to blue top to haveyours rebuilt. I will not reccomend redhead anymore after seeing how quickly mine got loose.