That's a restored 1961 Chevrolet Corvair 95 Rampside, one of just 10,787 made that year. I'd never seen a side-loading ramp on a pickup before. The slope looks too steep to roll anything heavy up or down, and if carrying something on it, I think that'd be murder on the ankles; I think they should've gone with stairs. In any case, these kinds of auctions are more about novelty than function, so I imagine it will sell for a pretty penny.
If old, weird trucks is your thing, there's more to see here.