That is a lot of work both to get the top off and to replace it onto another cab.
The top is both welded and bolted to the lower portion of the cab. Along the rear belt line you will find about 85 spot welds in addition to four bolts which cannot be access without having double jointed fingers. The bolts appear to have been installed prior to the inside top panel being installed so getting to the top of the bolts is not possible without first cutting some metal.
I have read where others have done this but having replaced the rear panel on my 54 I have been inside that area and it was very tight.
