I have a 1941 1/2 ton pickup. My new battery keeps going dead after two days of not starting the truck. Now I've had the battery checked by three different stations and each of them said the battery, 8 volt Interstate, is fine. I have replaced the starter, generator, regulator, all cables and grounds, checked to make sure the lighting switch, heater switch, defroster switch, fog lamps, brake light switch, and spotlight are not on. They are not. I am baffled and need help.Thank you so much. ps I have installed a battery cut off switch for now.

First of all, you would be way ahead if remove the 8 volt battery and go back to a six volt battery, which was original equipment. Down the road you will probably find that you will have problems with the 8 volt battery. With everything up to snuff on your truck, a six volt battery will work just fine. There are many threads on this site concerning 8 volt batteries so you might want to do a search to find the discussions.

Okay, on your "possible" battery draw. Disconnect your ground cable and then connect a continuity test light to the battery. Make sure that the continuity test light is powered by the vehicle battery. Connect the lead on the test light to the ground cable and then touch the pointer of the test light to the ground terminal on the battery. If the test light illuminates then you have a current draw somewhere. Isolate each electrical device on your truck until the light goes out. When it goes out then you have found the culprit. If there is no light when you connect the test light then you probably don't have any current draw.

Good luck!

8thairforce
When u start isolating items dont forget to disconnect the generator at the cutout/regulator as JunkYardDog will testify these can stick closed and drain the battery as well.
Tony