Good luck. There's no special name. You got to look at the drawings - if you can find them - and sometimes you can figure out if that particular terminal has the wider section for the insulation crimps.
Just for kicks, lets see if Chrysler specifically used a double wide one on the '67 a-body left headlight.
View attachment 1715591749
I'd say probably yes.
But other places I'm not so sure they did.
For drawings I've had a little bit of luck with Mouser and similar companies having a link to APTIV/Delphi/Packard pdfs.*
I've also had some luck with smaller specialty companies with real photos of the items they stock.
Over half the time I buy the stuff and then find out they nitty gritty details when they're in my hand and I'm trying to put something together. *
Often I've been able to get two wires side by side on a standard terminal as long as the insulation is not real thick.
This is another advantage of marine wire. Not only it the higher strand count result in a denser conductive core, but the insulation is higher rated than GPT without being thick like GXL and SXL. TXL is probably another option for engine compartment but away from the engine and the insulation is not thick.
*Snip from a crib sheet I made for the Packard 58s in this post
Sources for Chrysler type wire terminals
You could try searching Mouser, Newark, etc for 5/16 female recepticles and terminals. Another option is call around to places like RI Wiring, Bill Evans, and Rob (crackedback) and see if they have what you want.
