1980 K100 Cabover Project/daily runner

First is the guts out of your speedometer ratio adaptor. Under all that grease is a 15/16's nut unscrew it to remove. Put a drill on the speedo cable. One to drill and one to watch. 1000 RPM = 60 MPH. If it works just replace the ratio adaptor and your good to go.
Second is a Kysor Cadilac temp sender in what looks to be a radiator hose connecting pipe. Thats wrong, it belongs in the water rail. There are many variations but most often operate the cooling fan, can shut down the engine.
Third is not so bad. Keep it close to original as possible.
Forth If that is in the oil pan that is the oil temp sending unit.
Fifth looks like the tach sensor. Dealer or what goes with your new gauge if it does not work with the old one.

 

Exception to number three: You said you were going to replace the two car batteries in it with three truck batteries. Your truck could have a 24V starter with a 12-24V series paralel switch. If either one of those units failed I would trash all of that and go to a 12V system. Check it out before you go swapping out batteries.

 

12-24 is antique, get more cranking power with 4 12 volt 1,000 CCA batteries. Run your Webasto for 10 hours and start right up every time.

 

Do all of them go to the starter? If not where?

 

Remove seres parallel switch. Hook all negatives to ground lug of starter, ground strap to frame and cab. Hook positives to starter solenoid, power wire from there to main breaker or breaker panel. Protect this power wire, if it gets shorted to ground, it can/will start an electrical fire.