What is this part?

[Dave]

The wiring on it goes into the car throught the firewall.  The black knob rotates, but I have no idea what it does.
The white paper was used as a background to make the mystery part more visible.
Anyone?   Bueller?

[mdsalemi]

Can you opne it? Looks like an auxiliary fuse box to me, on a mounting bracket...if it is, it might be for the radio or power antenna?

[Jonny B]

There was a thread by Alfred Esser about this fuse block. There are two of these blocks, one for the radio, and another that relates to the lights. See that thread (use the search function) and you should be able to get some information.

[Raymond]

The "knob" is a screw that holds the cover on.  If you notice it's two bakelite halves.  There are two ceramic fuses inside.

[ja17]

Yes a fuse box it is. The bracket mounts on the top mounting bolts of the brake booster.

[Dave]

Thanks Gents.  I never would have guessed it was a fuseholder.  One fuse missing, one fuse good. 

[ja17]

Hello,

Most likely, only one fuse  is wired up and the other fuse was never installed since it is not wired. Sometimes the second fuse is for the rare electric antenna option.

[KevinC]

Page down to near the bottom of the article...

http://www.sl113.org/wiki/Electrical/Radio

[Dave]

Joe You are absolutely correct.  I saw only one was wired as I put it back together - you could tell at a glance.
Kevin-thanks for the link.  That's it exactly.  Mine is on the drivers side.  Also, now that I've got my car back on the road, your car's twin lives!
Thanks
Dave