I just bought a rebuilt steering box and new pitman arm. I torqued to 185 foot pounds but the arm doesn't go any where near as far down the splines as the other one. There's still 3/4" of splines below the arm. The nut is flush with the end of the shaft. Is that ok?

I just went through the same situation. After a day of driving I retorqued and got a good full turn out of it. I believe I have about 3 threads showing. Make sure your pitman arm is aligned right. There is a master spline.

Same for us, I was told 2-3 threads showing is fine.

Pabst Boys did this swap. Their replacement pitman arm has splines showing above it, too.

The way I pressed a few bigger pitman arms on (2500/3500 pickups) is I would lubricate the threads with antiseize or oil and run the nut on. This would pretty much press the arm on fully. Remove the nut, clean the threads with brake clean, apply red loctite, torque nut to spec. Never had one come loose or need retorquing.

So it turns out it's not OK for the arm to not go all the way down the splines even though it's properly torqued. After wheeling 1 day this weekend the arm became wobbly on the splines even though the nut didn't back-off. I put at least a turn and a half on the nut to get it tight again. So that's kind of insane.

i think it was not lined up right to start, sorry.