Looks like making something to do the job will be easy. Making a look alike without a sample impossible and not really that important I guess.
https://youtu.be/Cmz8bzUsj7E?t=1038
If you can measure the footprint or even the area available and where the screw sits relative to the edge and it's dimensions and a height needed to clear the transformer cover is all we would need to roll you a design based on the Tek one shown earlier.
Yep, them's the buggers.
As these HP's use an IEC lead there's really no need to have slots for the mains cable but the feet do need to be long enough to give good clearance for the CRT cover to ground.
Remember, these also used insulating feet for the days when it wasn't frowned upon to float your scope.
1/ So length required is 40 mm.
2/ Screw CL to case side edge max 10.5 mm. (so 21 mm min wide and square)(see 4 and 5)
3/ Screw CL to case top/bottom edge max 15.5 mm.
4/ Back panel to case edge/rim step 2.2 mm (in case you want to step up over it and make the foot slightly larger to the case side edge.)
5/ Case rim width 3.2 mm.
6/ Standard screw: remaining meat at bottom of screw recess 13.5 mm.
7/ Screw allow 3.5 mm dia.
8/ Screw head/washers allow for 8.5 mm dia.
These should fit in any of the 4 positions.