Usally the nylon dries out & no longer holds tight enough for a good connection to be made-sometimes you can hold the switch together & get it to work, but once pressure is let off it no longer works. The 63 Chevy TS switch is a one year only for Chevy, but I am pretty sure it is the same as GMC 63-66. I had a 63 TS switch sent by mistake for my 64, it was the same as my 66 GMC TS switch. Of course, the GMC coulda had the column swapped out in the last 40 yrs, but it didn't look like it had been apart ever. Brian
