One 'problem' is the photo from the fleabay auction shows a different capacitor.
But according to http://www.actionpinball.com/parts.php?item=CAP0.1UF500VDISC
"NOTE: This new replacement part is MUCH SMALLER than the original 25- to 35-year-old original parts due to modern manufacturing methods. Do not be alarmed- this part will replace the larger original part and function just the same, despite it's smaller size. Measures 1/4 x 5/16 inches rectangular (6mm x 7mm)."

104 is the correct capacitance according to http://robotoid.com/appnotes/electronics-capacitor-markings.html
but I don't see any voltage marking and according to https://www.avx.com/products/ceramic-capacitors/surface-mount/y5v-dielectric/ the Y5V means only up to 50v.

I'd do some more research before using them in a 500v application.

Fleabay is AWFUL for bulk electronics. Youll get poor or counterfeit chinese crap. There are several dedicated pinsiders here that supply quality american, japanese, taiwanese, korean, and A++ grade chinese parts. Look them up.

G-P-E is one of them. 45 cents each: https://www.greatplainselectronics.com/proddetail.asp?prod=CCD-0.1uF-500V-P5

The cap shown in the Action Pinball link is a multilayer ceramic cap. For the most part - this is what all the ceramic cap manufacturers have gone to and the old, round ceramic disc caps are being phased out by most manufacturers.

The cap shown in the GPE photo is a ceramic disc cap. This is an old style cap and often have to special order these to get them in this voltage rating and lead spacing. I'll probably switch over to the multilayer caps in the future.

Either one will work, Both are smaller than the old originals.

As YeOldPlayer mentioned -- the caps in the auction photo are different from what you got. The auction caps were clearly marked '2KV' or 2000 volts, the caps in your photo have no voltage rating on them. Maybe a clearer photo showing both sides? Based on size - they appear to be at least 500 volts but they should be marked.