I bought the latest issues pf both "4 Wheeler" and "4 Wheel Drive" and one of the mags had an article on putting an NV5600 in a '78 Ford F350.
The article gave the name of a company that makes a replacement front cover plate for the 5600 that DOES NOT have the integral bell housing but has the correct transmission bolt pattern. The project at hand was a Ford but other adapters are available. This repalcement cover allows you to bolt the 5600 to the current bell housing. It does require that the transmission be diaaseembled to make the swap.
Also need is a clutch disc with a 1. 375" X 10 or 1. 500" X 10(depending on the version of 5600) hole to replace the Getrag disc which is 1. 250" X 10.
Other items (cross member relocation, drive shaft lengthening/shortening, new hole for shifter, new bracket for transfer case, different pilot bearing, etc. ) may be needed.
Sorry, I can't be more specific on the article but I don't have the mags anymore.