[markeb01]

If I ever saw a 60-66 frame with no X in the center I would just assume it’s a 63-66 chassis. The stock 60-62 frame is basically what old school convertible cars received. Many passenger cars used a typical perimeter frame with straight across crossmembers (similar to a 63-72 truck chassis), while the convertibles received the huge reinforcing X to make up for the loss of body strength when the roof was removed.

From a barnyard engineering standpoint it would seem IMHO the 60-62 X frame is far stronger than the comparatively flimsy construction of the 63-72 chassis. GM propaganda at the time claimed the new chassis was in fact stronger (and certainly much lighter), because the frame rails were now tempered steel. I’m not sure I accept that argument as valid, since I’ve seen many perimeter frames bend under the weight of a heavy cab over camper, and I’ve never seen a 60-62 frame allow any deflection at all unless damaged in a wreck.

It would seem removing the full X support from a 60-62 frame would be dangerous, since the side rails are shorter in vertical height than 63-72 frames, are supposedly not tempered, and were not engineered for the absence of this critical component.

If you replace the original torsion bar front suspension crossmember with the later coil spring version, the small anchor crossmember at the rear of the torsion bars can also be unbolted and removed.

If your question is would it be okay to slice out the X member from a 60-62 frame to approximate the open space and convenience of a 63-72 frame, I would recommend swapping to the entire later chassis instead.