These have been on my 60 k10 for decades, maybe longer. I like them, especially how they match my Centerline Convo Pros.
In the 90's one of them stopped working, after a long search I found replacement cams for one that was broken in half. I've searched some forums and found out little about them. I've always liked how easy they were to engage and disengage, and have never had an issue with them coming unlocked.
Did the factory 60 k10's come with a full time setup in the front which didnt have hubs, but rather sealed units that lock in when torque is applied via in 4wd? Is that the factory location of the 4wd lever decal? I wouldnt think it would be behind the rear view mirror...