This is from a GMC of the same year and size. I assume it is the same.
In the GMC Master Parts Bok 7.6920 is called "horn button contact", 7.7000 is "horn button insulator" and 7.7150 is "horn button spring". If you replace the contact make sure there isn't paint on the surfaces where the top and bottom contacts meet. Got one like that from one of the old truck parts vendors on time. Looked good, didn't work.
'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.
