I'm not sure if a 30 series cab mounts are the same as 10 & 20 series,the 1 ton frames are taller,but might use the same mounts anyway..
We removed many cab mounts and spring hangers at the junkyard using just a 3 lb. sledge and a cold chisel (to avoid burning the place down in dry summer weather,when using the torches was taboo!)--after awhile we found a all steel camping hatchet in a junk cars truck,and my co-worker decided to use that instead of the chisel one day,and found it worked slick..(with safety glasses or face shield of course)..
You put the blade against the rivet head,or between the frame and bracket where the rivet is,,and give it a few good whacks with the sledge..the rivets pop right off ,a lot easier than we thought they would,and the hatchet was safer to use than a chisel,less chance of hitting your hand!..