I helped my dad build one when I was a kid. The ram was a surplus (or maybe used) RAM from a John Deere backhoe (we lived minutes from the John Deere world headquarters) and the rest of the parts it took my dad about two years to aquire. My grandparents owned a salvage yard & used auto parts business, so the axle was easy to find...it was a couple feet off the ground, making it harder to load the logs, but easier on the back once you got them up there. Plus it was legal to tow, complete with lights and license plate!
The engine was a big old 8 hp, you had to manually wrap the pull rope around the pulley to start it. It ran great, my dad was a deisel mechanic so this was nothing to him. I'm still amazed by some of the things my dad built instead of buying, like the air compressor that I used to paint cars...the tank was an air brake tank from a semi tractor...it was huge!
Having worked in many fabrication shops that built every thing from cable reels to tractor & truck cabs, I'm impressed with your skill. The gas tank in the axle is pretty sweet!
Thanks for posting the pictures which jogged alot of memories of my father. Thanks again.