bit of a long short, but does anyone have a spare one of those: Ducati don't make them anymore, so looking anywhere I can for one.
A quick google showed US dealers still stocking, so you might find one in Europe - have you tried many dealers? Ducati Omaha has them in stock.
I just checked Ducati Omaha and it says the part is discontinued. do you have a link? the part number is 561.1.017.1A, there is also a later part that is similar but has the same result, it is 561.1.019.1A
Didn't notice it said that - it adds to cart here but shipping is silly money... https://parts.crosscountrycycle.net/p/Ducati__/Number-plate-holder/42749320/561.1.010.1A.html
Adds to Cart at Ducati Omaha too... not sure if the link will work but put the part number in without the dots in their search box.
561.1.017.1B 2001 Ducati 748 Plate REAR FRAME - REAR FOOT RESTS 561.1.017.1B 2001 Ducati 748r Plate REAR FRAME 561.1.017.1B 2001 Ducati 996r Plate REAR FRAME-REAR FOOT RESTS 561.1.017.1B 2001 Ducati Monster 400 Plate PLATE HOLDER - REAR LIGHT 561.1.017.1B 2001 Ducati Monster 600 Plate PLATE HOLDER - REAR LIGHT 561.1.017.1B 2001 Ducati ST4s Plate NUMBER PLATE HOLDER 561.1.017.1B 2002 Ducati 998s Plate REAR FRAME-REAR FOOT RESTS 561.1.017.1B 2002 Ducati Monster 400 Plate PLATE HOLDER - REAR LIGHT 561.1.017.1B 2003 Ducati 748 Plate NUMBER PLATE HOLDER 561.1.017.1B 2004 Ducati SuperSport 1000 Plate NUMBER PLATE HOLDER 561.1.017.1B 2005 Ducati Monster 400 Plate NUMBER PLATE HOLDER - TAIL LIGHT 561.1.017.1B 2005 Ducati Monster 620 Dark Single Disc Plate NUMBER PLATE HOLDER - TAIL LIGHT 561.1.017.1B 2006 Ducati Multistrada 620 Plate Number plate holder - tail light 561.1.017.1B 2006 Ducati Multistrada 620 Dark Plate Number plate holder - tail light
Hi - I got the attached in a box of 748 bits I bought but never figured out what it was. But it looks about right for what you're looking at ( I think ?). Anyhoo, it's a bit shot and would need stripping back and repainting but you can have it for the cost of the postage if it's what you're looking for ? ( no part number on it so I can't help there )