Trying not to screw up

[DryFly]

Finally pulled out the old univolt and am ready to install the Intelipower PD9245. I want to use the old fuse block out of the univolt, so I carefully removed it, then I realized I don't know anything about fuse blocks except how to replace a fuse!
When I pulled out the fuse block I carefully documented what wires go where, and all would be well except for the 2 black wires that came out of the back of the fuse block and attached to the univolt. One wire went from a bolt coming out of the back of the 50 amp fuse holder and ran to one of the aluminum cooling fins on the univolt. The other one came off of the copper strip at the base of the fuses and ran back to the big coil area of the univolt where it was attached to a copper wire that came out of the coil. I've attached a photo showing the 2 wires before I removed the fuse panel, a photo of the front of the fuse panel with wires attached, and a photo of the back of the panel.

So here's my question - do I need to replace the 2 black wires that came off the back of the fuse panel? if so, what do I attach them to?

[TG Twinkie]

In the third photo, there are 2 hex nuts on the back of the fuse block.
Connect the negative wire from the PD 9245 to the nut on the left. Connect the positive wire of the PD 9245 to the nut on the bottom. Notice the the bottom nut is on the screw that is in the center of the copper buss bar. This is the positive side of the 12 volt DC.
You need to be careful where you mount the fuse panel. You do NOT want the positive terminal to come in contact with the skin or frame of the trailer.

[DryFly]

Thank you so much for your quick response. Your explanation makes sense now that I look at the way the univolt was wired. I assumed the wires led from the fuse block to the univolt coil - backwards from reality. I would have never guessed - but then when dealing with electrical, I don't like to guess.
I'll mount this to a wood block with the positive wire and negative wire separated.
Thanks again

[DryFly]

Any thoughts on how to recycle the old univolt? It must have 10 lbs of copper.