edit: whoops I'm thinking series.. were faireys around and kicking in 90/110's / Defenders? not sure.
Fairey od's are available all over, used. The rebuild parts are available.. They hold small amount of oil and leak, and so many of them develop a loud whine hence the need to rebuild. 4-800$$
Global Roamer makes the Roamerdrive. Brand new parts, new(er) design, holds more oil, shares it with the transfer case so they don't have the lubrication issues of the Fairey. Perhaps not as well long term tested, but all reports I've found are good. $1500
Install is bolt on, with some sheetmetal cutting to mount the shifter handle
"Yeah, make sure its a flatbed...."