For basic questions, if you want to learn more about any one model transmission or to find service, parts, and operators manuals for for most all Eaton, Fuller, and Roadranger transmissions as well as driveshafts, clutches and so much more please try the Roadranger Literature Center
It's a great place to start!
These first three post show how a transfer case may be mounted to a Roadranger, they were copied from another thread, thus why they appear out of order...
Just this weekend I saw one with a bolt on transfer case in a 1 ton Chevy truck.
I am pretty familiar with the small 10 speed Roadrangers, model RT610, RT6610, and the RTO versions, and there is not a factory way to bolt on a transfer case that I know of. The adapter I saw this weekend was shop made, but simple and seemed very well thought out. Until yesterday I would have said you can't do it.. but I did not have a reason to try it either.