[66Submarine]

'62 was supposed to have coils and torsion bars like that; thanks for the extra confirmation of the lack of a VIN on the GMC stuff.

AFAIK '60-'62 all had rear coil springs with the torsion bars and x-frame, then when they made the changeover in '63 to the '63-'66 ladder frame and front coils they went to leaf springs on the rear (this is only for the 1/2 and 3/4 ton 2wd trucks, of course).