Hi Scott
First here is the information on the horn button
Found these a couple of years ago as NOS sorry only bought the one which I used on my HUP. But it hopefully will give you some part numbers.
Now to your question about the sender units for the M35 my volt-ohm meter started giving funky readings about that time so I didn't get to check the resistance of these units. So after your reminder I send an e-mail to an electrical engineer who happens to collect M35s so hopefully he will get back to me with an answer soon.
Now the M35 sender looks like it would fit
Can someone confirm what the senders range was in Ohms for CMP?
Strange you should mention the fuel gauge sender today as I was working on one of the senders in my HUP today that has not worked since getting the truck back on the road last month. Turned out the cork float had sunk.
Cheers Phil