Those ain't 4x4s - they are 6x6s!
The first skoolie I ever worked on was a Chevy 6x6 - I think it was about 2 windows shorter than the white bus in this thread. It was and still is my favorite skoolie of all time. It was the district's "mountain bus," and even had sander tubes mounted in front of the rear wheels.
If I can ever find out where it went . .(sigh) . . I think it became a storage shed in a back yard or wood lot somewhere in the hills around here.