fuse holder ?

[Artie in Miami]

While replacing some of the rotted vacuum lines on my '86 Suburban C20 350ci engine, I noticed a fuse holder on the firewall that fell apart and fuse gone. I am wondering what this supplies power to and what size the fuse was. The wires are pretty heavy (maybe #12 wire) so I assume it must be important. I am attempting to put a pic !

[kwmech]

Trailer plug. The attached wire should be blue and if you follow the wire it will go to the frame rail or be bundled up close by,

[Artie in Miami]

Just came in from under the truck (got rust in my eye) and saw that the wire goes into a tube that goes to the rear of the truck. Thanks for the reply ! What size fuse do I need when I replace the fuse holder ?

[kwmech]

If the fuse holder still works--20a -----When they get this old they usually deteriorate to where they just fall apart. You can splice in a spade style fuse holder if needed.

[Artie in Miami]

Yes...fuse holder is shot...I have several varieties used on my boat...thanks !