Hey daver,
He is correct those are main fuseable links supplyiny power to everything but the starter itsself which is connected to the positve battery cable.
So do you need lights ,ignition alternator and horn ?
Kinda answers your question about how important they are.
You can cut back the wires and install new fuseable links with new connectors if you want ,that depends on how badly corroded the wires are .
You can get an eyelet terminal end about a 1/4 inch hole size ,cut the end of the wire off near the black connector and crimp the eyelet on and then using a universal cable end for the battery screw it on top or the side bolt will work .
Dont use an inline fuse holder ,they get to hot become weak and leave you in the damn rain snow ,wilderness at the wrong damn time always.

Use a new link or a repair what you have with some new connectors and a new battery terminal end.
IF the battery cable is ok, check down the cable and see how bad the corrosion is if its too far down ,you can get a new cable that will have new male spades just like the old cable and just plug the links into it. Or new ones if needed.
These cables corrode alot after time and cause tons of electrical problems, my advice here is do it right ,it will last longer and piece of mind goes along way when yer wheeling in the boonies...
Good luck
Gary
