A suggestion from one of the guys over on OldGMCtrucks is:
To me it looks like a cap that would put on the end of a cable sheath, like the end of a park break cable. I remember my stock ones had a cap that looked like that and fit into the bracket on the frame. Not sure about the dimensions but I think it would be close.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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