DW,
I got quite nervous..the Sharks wouldn't commit to the fact they were 100% sure it was the dimmer switch. If that was the case, in light of my previous post I would have to commit Hari Kari.
To avoid that unpleasant task, I hustled down to the shop where my naked cab rests on a dolly. I am now 99% sure the item you have circled in your picture is the dimmer switch.
If I am wrong, I will send you a case of Jack Daniels post paid, post haste! Feliz Navidad.
Stuart