I just completed a project that's been in the works for a couple of years. I started out to repair a steering gear for a friend's '68 CJ5 V6. It was in pretty bad shape. I decided to use an M38A1 gear that I had for parts. By the time I got it all back together he had sold the '68. The buyer is probably wondering where the steering gear is  . So, I decided to put the "new" V6/A1 gear in my CJ3B.
I pulled the LF fender for better access, and after disconnecting everything necessary, I wormed the old gear out. I pulled the steering wheel off by sliding a large bolt into the tube and rattling on the head of the bolt with an air hammer.
This is when I found that the M38A1 worm shaft is one inch longer than the CJ3B shaft. I didn't care for that, as there is little enough room between the seat and the steering wheel as is, but at this point I was committed.
I decided to put the new gear in place without the outer tube so that I would not scratch the tube, and to gain a little working room. It really helped, but I should warn you, you need to slide the tube clamp down the shaft before starting, as it won't go thru the hole in the floor on the tube, and barely will by itself. I used washers between the gearbox and the frame to make sure that the shaft was centered in the dash bracket, then installed the tube. I then loosened the three gearbox bolts one more time, tightened the dash bracket bolts, then tightened the three bolts for good.
I had left the pitman arm nut loose so that I could make sure that the steering gear was centered when the wheels are straight ahead. I had to take the exhaust manifold off so I could get to that nut with a wrench, but that's OK, I was going to adjust the valves while I was in there anyway, and it just makes that a little easier too.
I put the steering wheel on and right away had to get in the jeep and see how that extra inch was going to affect things. It's closer to my belly than before, but doesn't actually rub . Time will tell whether I like it or not. All that's left is to get some GL1 gear oil & fill the box, adjust the valves, put the rest of the jeep back together, and test drive it. I'll let you all know what I think as I drive it, who knows, I may have a "V6/A1" steering gear to sell. BW