'60-'66 Chevy 4wd w/rear trailing arms

[pinefieldfarm]

I came across a '65 Chevy 4x4 longbed that someone was driving locally and got a chance to take a close look at it. The truck was to the best of my knowledge a 2wd to 4wd conversion because it had an open knuckle (Dana 44?) front axle with leaf springs and the stock coil spring/trailing arm rear suspension. I thought it was so cool that I've decided to convert my '61 2wd longbed to 4wd.

Has anyone here done this conversion or seen anything like it? Or did GM make 4wd trucks like this for any special reason? It seems like it would be far superior to leaf spring rear suspension, but would be limiting in regards to modifying and lifting the truck or rear axle.