I put one in my 66 and I can't seem to drive it anywhere without tooting it at least once. Mine's one of the newer ones you can get at most local auto parts stores, not the old ones like yours. Have fun with it.
Rance
66 C10 FS/LB 292/4-spd manual (I also enjoy Hang Gliding) I'm too sexy for my hair, that's why it isn't there