Jim Carter (and Classic Parts and Chevs of the '40s) 1954 "reproduction" wiring harnesses are almost the same. They work very nicely in 1954 3100/3600/3800 trucks.

The wires have plastic-coated wiring (as in 1954) and the are the correct 6v gauge (and the correct colors). 6 volt gauge wire will work fine with a 12v electrical system (which works with thinner gauge wire).

Only custom-made harnesses will have the extra leads used with a Hydra-Matic transmission. You will have to make those leads/wires.