Saw this on eBay;
https://ebay.us/m/Y9rjO3
It was bolted to a later set of Sid forks, on top of the legs. Messaged the seller to point out the 'extra' bit, asked if he'd list it separate.
Anyhow, he has, and now it looks odd - has he pictured it from the back? Is that why it looks strange...