1960 was the first year of the corporate 4x4. Longbeds only. 1961 was the first year of the 4x4 shortbed.
You have it backwards. The longbed 1/2 ton 4x4 didn't come out until '61. Shortbed 4x4s and the longbed 3/4 ton 4x4s were both available in '60, as well as having been available from '57-'59, along with a 1 ton 133" wheebase mode from '57-'59. GMC had similar offerings, plus a 114, 123.25, and 133 inch wheelbase 1 tons.
I have found no listing for a factory built '60 Chevrolet 3/4 ton 4x4 though. I would suspect possible parts swapping. Does the truck in question have open knuckles on the front axle? That's a dead givaway that the axles have been swapped, along with possibly having a rear diff without a drop out 3rd member.
