willysmjeeps.com

and it has all Douglas shell metal connectors. All the lines to it also have Douglas shell metal connectors. Both sides are male, and they have a two way female barrel connector in-between. The problem is, the Douglas shell connectors won't snap together with that connection barrel. How was this dealt with?

I used silicone grease on my connectors to help the fit. On really tight ones i sanded down the ends of the barrel connectors. The newer white nylon barrels were slightly larger which seemed to need the sanding. the original brown barrels were an easier fit and I don't recall having to sand them.

The new rubber grommets are what's making them so tight. Use a dab of silicone as stated previously or some anti corrosion grease in the end of the connector and a dab on both sides of the rubber. This will help it slide together a little easier. You'll notice after they have been connected for a day or so that the rubber has taken a 'set' and is a lot easier to assemble. I had some so tight that I had to use 2 pair of vise grips to get enough pressure to mate them together.

is this with the Douglas connectors? They only have that little bit of rubber at the base. With the Packard connectors, I routinely have to use silicone to put them together.

Yeah, the little piece of rubber on the douglas connectors - grease it up and it will go together easier.