Sm420 Factory Reverse Light Switch

Steve's jeep came to us with a Sm420 already installed. The 420 is the elusive 1967 model with the factory reverse light switch built into the shift cover. The reverse light switch is however missing.
I have looked for 1967 model chevy trucks but can't find a listing for the reverse light switch.
Do any of you guys know the part number for the factory thread in switch?

 

If this is the one that screws into the top of the shift tower 3718016.

image5.jpg

 

With that setup you could make any SM420 have a backup light switch. My sm420 is 1953 or before..

 

maybe look into the bigger trucks these transmissions came in. they might have the switch listed there.

 

This threads into the shift cover on the right rear side.

What makes of bigger trucks do you suggest?

 

You can add the light switch to the rail on any sm420 and use the switch on the sm465.
Ill see if I can find the article.

SM420 Reverse Switch Adaptation

 

they were the ton and a half and bigger trucks. like grain trucks, dump trucks etc.

 

Thank you,
I will check that out. I was also going to see if by chance the sm465 used the same light.

 

They came in pick up trucks too. The one I am currently running was in one and my spare came out of a dump truck. I have the PTO from it too.

 

some of those pto's are cool. i would like to get one for my sm465 and run a winch or two

 

You don't happen to have a switch laying around with a part# on it do you?

 

no. mine are both pre 1953. They don't have a seal on the bearing retainer either, so if you are pointed downhill with the engine off, you're probably going to lose a bit of gear oil. Novak will machine one into mine for a price, but I didn't go for it. If you get this figured out, do a write up with pics so i can do this mod?

 

I added a reverse switch to my T-98. When I had the transmission apart, I found which shift rail was reverse, located it in the top, then found how much the rail moved, took a swipe at how deep the rail was off of the top of the cover, say, about 1/8", then added that to the thickness of the top cover (another 1/8") and then went about finding a switch that had a short-enough stickout (this is a detent-ball kind of switch), then I drilled and tapped the case, added the switch, and now it's waiting for me to get the right weatherguard connector and wire it up...

One of our members posted a 'vintage' solution on post #90,
Vintage T98, D18 and Overdrive

I have a few picts of what I did on post #116
Vintage T98, D18 and Overdrive

I don't recall the part # of the reverse switch I used. FWIW: it's out of an 80's era Ford T-18... I went thru a few with the guy at the parts counter looking for one with the right length stickout (GM ones are pretty long if I recall from this experiment). Also recall that late model GM switches use a metric #15 tap, and that is a biotch to find, had to order online. The Ford was some flavor of an NP fitting (1/4 NP IIRC).

 

Thanks for your input guys.
The sm420 that I am working on is the "rare" 1967 model with the reverse light feature built in/ drilled and tapped straight from Muncie's factory.
After much research I have found that a standard motor products NS18 is the correct back up lamp switch.