RM, you don't say what year you have. If you have early 48 it had a diff rear set-up with a big pad in back center, as the later ones have a "link" on back corners. The rubbers go into the link swivels, four rubbers on each side of cab. Problem may be the links are so rusty you can't get apart easily. Best to remove one end of bracket from frame and swivel down with oil in them to "break loose". Remove the two nuts on link at sides and wiggle out the top pin after you have one side bar off. Then,you can do other one on bench or out from under cab at least. I would wire brush or blast the parts and paint black before reassembly. Use new rubbers during assembly. Keep in mind "rust" which may cause the link pins/nuts to snap off or if you remove the upper mount off cab floor, they will most likely snap-off. They have a plate on floor near gas tank corner they thread into and you need to keep a count on the spacers between the mount and the floor and put same ones back in. The bolts on frame may break, yet they are just bolts/nuts and will just be less wrenching if they break and you can use new bolts there.
Wookie, I'ld like to know WHERE you are gonna buy Poly bushings for any of this old truck!!! I'm sure with limited needs they won't be making such animals. UNLESS, I'm just too unaware they have assorted taper bushings you buy by size???
Biggest problem I had on front mounts was something about some metal spacers in kit or ? that are not shown on the assembly man pictures. Seems like I put mine between the body and the pad, or was it on the bottom of frame bracket? Or....Never Mind! Been too long ago!

:rolleyes: