Carrier terminal box?

After reading, studying, buying, and learning a bunch about Goats, I saw something today I have never seen or even heard of before. Alex at IMP got a Goat in the other day. He called me and want to come look it over. I noticed a box (about 4 inches wide, 8 inches tall, and 3 inches deep) bolted on the inside front of the carrier. It is on the passenger side, not quite all the way in the front corner, near where the fold-down seat ends. It has a pigtail (with the proper Bendix connector) hanging from it long enough to screw into one of the customary power outlets that are located in the center of the front of the carrier. So I can figure it is a remote power source for some reason. Now for the strange part. It has three terminals on the front of the box. The top one has a spring-loaded cover that hides a circular two-prong plug, (similar to a common 110VAC plug) only it had two provisions for circular prongs instead. That one is marked 250 VAC. Under that there are two other screw-cap covered terminals. One is the usual (relatively speaking) Bendix three prong, so whatever could have plugged into the carriers outlet could be plugged in there instead. The other is a smaller four prong which I have never seen before.
I think at one time this particular Goat might have been an ambulance model. Coulld this box be related to that?