I had this same issue on my 96 too. I had some other miscellaneous alignment problems (which may or may not have been from sliding the front wheel into a curb doing a j turn on ice) which resulted in me replacing a lot under the truck: inner & outer TRE's, steering rack (w/ poly bushings), LCA bushings.

This, combined with SPC upper control arms, radflo shocks, new ball joints, 1st gen taco sway bar mod (all toyota OEM parts) was a great improvement from an under-maintained soccer mom car with 250k miles.
BUT, the steering rattling on rough roads still drove me nuts. So I pulled out the steering column and threw a couple tack welds on the slip joint as some suggested on here. There was no apparent loose-ness but I decided to try it out anyway. That didn't help.

I ended up taking out the steering shaft on the engine side of the firewall. I noticed there's a shock absorbing coupling above the rag joint that is a rubber piece sandwiched between two metal plates. One of the plates has slots, and another has pegs that loosely fit in the slots, allowing the rubber piece to flex about 1/8" rotationally. Sure enough, that was what was making rattling noise. It was functioning as intended. So I put it back. I've done a little brainstorming as far as replacing the rubber with a 3d printed piece of polycarb or something to prevent it from moving so much, but it hasn't been a priority since it functions fine.

Sorry I don't have pictures, it was a while ago. I've never seen one of the different style ones.

My 2 cents, hope it helps. Let me know if you have questions.