Denny,

For back-up lights on my 54 1/2 ton Hydra-Matic (that has a back-up light switch), I am going to try to attach a backup lamp to each of the two 54 tail lights.

I have obtained a NOS pair of black back-up lamps like the one shown on the Suburban tail lamp in this JC article.

The other backup lamps that I will be mocking up are used GUIDE B-31 lamps that I will paint black (if I use them).