[Snake72]

1972CheyenneSuper, I'd be glad to show you how we did it. I should have taken more pics of the install to document our process. I'm sure there are several different ways to install this, probably all depending on the starting point of your cab and metal. My cab, although it looks pretty clean in pictures, was horrible. A and B pillars nearly gone, no driver side rocker and passenger rocker was metal tape covering holes. The cab corners were metal tape and a field stone spray foamed to cover a hole. No joke. Old grandma did her own body work on this truck which consisted of rough bondo, metal tape, and blue paint brushed on over rust. She did her best haha. So we had little to use as original reference. We cut out all the cancer just to see what we were working with. We also had a rotisserie, made things much MUCH easier but not necessary. I read and re-read every thread on this site about floor replacements and was a huge help.
1) brace inside of cab, we used tubing to span door frame, hinge bolt to striker area. Then welded cross pieces from back of cab to firewall and diagonals. You don't want a flimsy cab or torqued/misaligned cab when trying to fit new floor
2) we then cut out cab corners, rockers, A, B pillars just to see where all the seams were.
3) used a spot weld hole saw (get one) and worked over the back of the cab to cut out all the spot welds holding the floor to cab. Half the driver side welds were already broken...nothing even holding the floor up on driver side. Seat belt bolts were ripped out by hand....
4) once rear of floor is free, we used a sawzall and cut front of floor about 1-2" from firewall flange and pulled the floor out.
5) Spot welds were then cut on front flange and used an air hammer to peel back that 1-2" left over flange.
6) Fit new piece, call some buddies over to help, not a 1 or 2 person job. Use lots of vice grips to hold and get it fitted right. Trans tunnel and areas by the A pillars may take some convincing.
7) Make sure front and rear seams are fitting well, we used 2 bolts to temporarily connect the rear cab and floor while welding the front floor to firewall
8) Plug weld floor in, using holes were old spot welds were drilled out on firewall flange and back of cab. We even drilled some new holes for extra welding.
9) We worked from A pillars in to trans tunnel and made adjustments to tunnel fitting
10)plug weld the back of cab. Easiest part.

After floor was welded in we started fitting A and B pillars. A pillars get bolted to floor and only one way they can go in, not much adjusting. B pillars were easy, just take your time and fit as good as you can.

The cab corners also lined up perfectly, however I had so much rust in mine that we used the entire replacement panel on both sides. We had to cut out a lot of metal from cab.

Im probably missing some info but its really not bad. This is my first ever project and my FIL had never done anything this in depth but we worked through it without issue. Just take your time and think it through. Literally all the metal from the trim line down is new in this truck, we had zero reference to go off of and the doors fit better than new. Good luck!!