Converting to 4wd ?s

[Zukinut]

I posted this in the drivetrain section but i wanted to post up for the 4wd guys as well.

The build is starting. The longterm plan for my 68 F350 is converting to 4wd, putting in a cummins and a late model NV4500 or 6spd.

My question is, did ford make a factory F350 4wd in the bump/dentside years. If not can I get a F250 front axle and convert it to dually outers? Or must I get a late model F350 axle. I wanna start looking for parts now but I need to know what to look for.

Does anybody have any experience with this. Does anybody have any of these parts,ie:springs, hangers, shackles, etc.

Thanks in advance,
Will