1966 GMC 3/4 Ton Ignition question

[hammermouse]

I am working on a new to me project. I was able to locate a 1966 GMC 3/4 Ton 2WD that I am looking to rebuild/restore. Sorry for the long post....

When I received the truck, I had one key and one working lock (the door). The ignition lock was not in the switch and you used a key (or screwdriver) to turn the switch. I want to replace the switch/lock so that I have matching locks. No big deal I thought until the parts don't add up.

My ignition switch also looks like an aftermarket replacement (and appears to align with those used in a 74 Chevy). It is too small for the hole and doesn't use the original bezel. At first I purchased a new lock cylinder and bezel from LMC. When I went to use it I found that the bezel was too large (diameter) and the lock cylinder had different connect points into the switch. So I figured I'd replace the whole switch.

I purchased an AC Delco switch (D1437F) which is supposed to be correct (per AC Delco). It also aligns with what others point to at LMC truck, Bobs Chevy, and even OReilly's. When I go to replace it, I found that my ignition switch is a 4 wire and the replacement switch is 5 wire. When searching, I found several threads showing a 5 connector switch. OK, so I have both the original Service Manual and the original wire diagram book from GMC (found cheap on ebay and neither are reproductions). According to an original wiring diagram book the 1966 GMC I1500 only had 4 wires to it. The wiring diagram doesn't reference the dark green ground wire that I've seen mentioned on other threads and forums. I figured, no big deal...a ground is a ground and I can add it.

But then I go to put it in and the switch doesn't fit the hole. It's just a smidge too big. If I removed some of the flat spot (minimize it some) I believe it will fit. But...again....I realize that the new bezel is designed for the Chevy flat area around the hole and not my countersunk ignition switch hole. I also tried a BWD switch from OReilly that supposed to fit and it is almost identical to the ACDelco one I had (same crappy jam 'nut' and same diameter). The LMC ignition bezel DOES fit both the BWD and ACDelco switches, so they appear to be the right size...just not for my dash hole.

So my questions are:

- What switch do I use. Should I just adjust the hole and use the one that I have? Or is there a better one. (if this one, is there a better Jam Nut available as the one that comes with it is CRAP - thin stamped metal that you can rock back and forth over threads).

- Is there any way to obtain an original GMC 1966 bezel ring that fits the countersunk hole? It's definitely a factory dash with a factory hole.

- Did some factory glove boxes not have push button latches? Mine doesn't have one so I have to figure out how to modify it to add one or replace the door. The place for the striker is there, just missing the hardware.

New Switch:


Original Switch:


Diameter difference:


Dash with new bezel sitting in it:


Dash hole:




Thanks in advance for any help!!!!!!
Geoff