Originally Posted by 3B
Hy TGP, how many batteries does your truck have? The device you seak may be a series/paralell switch, these were used when an engines starter was 12 volt, but the trucks electrical system was 6 volt, the switches were also used later on 12/24 volt systems, hope that helps.

Thanks for the reply.
I am very aware of a series parallel switch. That is not what I'm looking for.
Right now it has one 4D battery. not sure what was original,probably two six volts.
Thanks
TGP

1951 GMC 650 Diesel
1958 GMC 550 Wrecker
1964 Chev C-80 427cid Tandem
1947 Dodge WDX Power Wagon
1977 Chev K-30 400 cid
1984 Chev K-30 Cummins 6BTA