blackwolf wrote:

It depends whether you want it to look nice, or look as though someone has hacked half the body off!

If the former, then you need the hicap or chassis-cab lower rear bulkhead. If the latter, you need an angle grinder and some cutting discs.

Unless the rear body is very poor I would think that the sale of the body would more than cover the cost of the bulkhead, although finding a good hicap bulkhead may not be easy.