Found a 86 crewcab dually

[86lovelongbeds]

I am new to the site just posted in the welcome area. Thought I would share the truck I found today and ask a question.
I happened across a crew cab dually 2 wheel drive in my search for a 4x4 crewcab, it is a 1986 with 79k original miles, 454 auto. Has original paint and original interior in fantastic shape, headline isn't even sagging. I was amazed when the guy started it, it sounds like its new. It has zero rust and I mean zero, I was shocked because my 86 has a lot of rust. I almost bought it but was not sure how easy it would be to convert it to a 4x4. The guy only wanted $2,700 for it.

The question I have is how hard is it to swap it over to a 4x4? I have seen a couple posts about the swap but not much info on it. If there is some info on it link me to the thread. Thanks in advance!