Here's something I haven't seen brought up, how tight are the box bolts or is the frame weak/thin at the mounting points? Same as for the idler arm with this same question.
80 lbs-ft. torque. All 3 bolts. The 2 bolts for the idler arm are torqued to 60 lbs-ft.
The bolts have anti-collapse bracing in the frame so essentially it's like the sway bar mounting. The "problem" lies in the fact it acts like a sewer tube for the bolts, so any moisture that gets in there gets trapped and just rusts the bolts away. When I pulled the 84 apart, I yanked the box and pulled out 2 of the bolts no problem. The bottom bolt came out and was about 1/3 the size of the rest of the bolt due to corrosion. Looked funny and was so necked down it looked almost like pencil lead. Amazingly it still came out like normal. Ran a bottle brush through it to clean out the hole. EDIT: Just to add, I put a film of wheel bearing grease on the new bolts where they go through the frame rail as a peace-of-mind thing. Maybe they'll last another 20 years. Oh, wait, that was almost 20 years ago I did that! D'oh!
Don't forget those "special" stop-sign washers on the bolts. There's a reason they're shaped the way they are.
Steering gear mounting bolts and washers:
GM p/n
Bolts-
9430763, 7/16-14 x 5.75" for the long bolt, need 1. (Was over 4x the price of the shorter bolts when I got them from the dealership, so watch out). Discontinued. Be wary of using hardware store bolts here. This is a crucial component.
15590234, 7/16-14 x 4.625" for the short bolts, need 2. Still available from GM. $3.94 list price, each.
Stop-sign Washers-
14074908
Usually all 3 bolts have them. Still available from GM. $2.39 list price, each. Normally sold in a bag of 10.
Also, a note about the YA, HX and WS steering boxes. The YA is the direct bolt-in version you can use from other G-bodies. The HX (higher effort) and WS (lower effort) steering boxes are from F-bodies, and have a bit different of a turning radius than the YA box. Something about one using 16" wheels vs 15". I don't recall. They'll bolt in too, but they use a different length pitman arm so you'll need to get one for a G-body 800 box. The effort is affected by the pump pressure and torsion bar diameters, so there's that, and honestly, it doesn't seem to be much of a difference from anecdotal evidence. So not changing anything else but the box isn't going to automatically make one box react much different than another.
The internal stops are also different on the F-body boxes to net you a slightly shorter turning radius than the G-body's original turning radius. LH turns can be "fixed" by swapping the cover from a G-body box to the F-body box, but RH turns can only be adjusted by different thickness snap rings inside the box. As-is won't affect turning radius a ton, but still there. General driving around town you may not even notice it that much unless you do a lot U-turns. They ALL have 12.7:1 ratio, so they're all considered quick ratio boxes. That doesn't change. Don't listen to anyone claiming the HX is the box to have because it is supposed to have the quickest ratio. That's just some BS.