This 1963 one-page double-sided brochure printed in Canada announces the new Wagoneer and Gladiator models. What I found interesting was on the back. The chart shows the electrical setups for all vehicles as of 1963. I was surprised to see that while the Surrey DJ-3A still had the 6 volt battery option, the standard Dispatcher DJ-3A did not. I was surprised to see the FCs also had a 6 volt option still.
It is possible this was unique to Canadian made jeeps, but I can think of no reason that would be the case.