Unknown electrical component.

It is 3 circuit breakers connected at the top by a common strap. Center red wire also has a smaller black wire attached with it and also has a large washer installed on top. Possibly one lead from converter, one to battery, one to fuse panel or other high current load. The black wire on the right is not connected, just loops in and out of the pic, most likely excess ground cable. After another look the circuit breakers appear to have manual reset buttons on the bottom of them.

its 2 12v circuit breakers on what a appears to be a mounting bracket for it

You definitely can see the black ground cable on the top connect to the metal bar that is ground on both sides to frame ground. The three RED cables are going to something Bakelite...

The whole thing doesn't appear to be very deep but that may misconceiving.

Need another angle on the photo to be more helpful...

It has both positive and negative cables terminated on the device.

I guess it could be a DIODE BASED battery isolator. Maybe there is HEAT FINS if you could see a different angle on the photo.

A modern day DIODE BASED Battery Isolator looks like this


???
Roy Ken

Can not see enought to be sure but it from the photo I think the O/P's suggestion is correct,,, Just a junction block, nothing more.

Diodes I do not see. But they might be hidden.

Sorry, my host-er is sometimes erratic. I was able to get home and get a better look, for anyone that's interested, it's actually 3 circuit breakers tied together kind of a distribution block. Don't know why it's not covered at all.

Hard to see behind the buss Bar but, it looks like two 12v circuit breakers.

12v circuit breaker

I don't see a picture to try to identify what ever it is. :)

This is a wild guess but it looks like or'ing diodes. Two power diodes that have a common cathode and separate anodes. It's called or'ing because it takes tow independent 12 volt sources and connects them to a third point via diodes so if one source goes away or shorts the other source is still able to provide the power. As I said though a truly wild ass guess.

Sorry I should have clarified, it is definitely the power (positive) side.

looks too me to be all the ground wire attachment point or where the positive wire from the battery hooks in if it is that or not i would be taking all the nuts off and cleaning them up to get rid of the corrosion and rust then put them back on and coat them with anti seize compound or grease i woukd be checking with a volt-ohm meter first tho