MikeC,
If you have/need the circuits that you asked about, you do not have "something so simple as a 62 year old truck":
1) Temp Sender (green wire)
2) Oil Sender (lt blue wire)
3) AC compressor (black wire)
4) Fan Fan (grey wire)
5) Tach (purple wire)
None of those circuits were/are standard equipment on a 1953 Chevrolet truck (62 years old). Do you have those components on your truck?
You might want to describe/list what electrical equipment you have. Maybe someone familiar with the EZ wire 12 circuit system will be able to help?
When you refer to the fuse block, presumably that is the EZ wire fuse block?
Whatever EZ wire fuse-block "circuit" you are not using could be used for your backup lights.
