These are chassis straps for a 4010. It's a JCM800 50w 1x12 combo, a rare bird. Far more common is the 2x12 version of this amp and those chassis straps are cheap plastic that always crack.
Here's the current one. Obviously, I can reuse the existing straps. But this cab, up close, looks like it was dragged behind a truck.
So this is the next one and I want to use something a little different, but still somewhat original looking. Also, I plan to sell the old cab and those original straps will help the value.