As Redheeler said, there basically was only one common Cube faceplate, and it most often had a Rage 128 faceplate. A few Cubes came BTO with either a 2MX or a Radeon(retroactively named the Radeon 7500).
The Rage 128 faceplate will fit a 2XM(regular, not twin view) as well as a Geforce 3. The Radeon/Radeon 7500 I believe had their own face plate, but as the Cube specific card was uncommon, the Cube-specific faceplate for this is as well. A beat-to-heck Cube with the remnants of a Radeon sold on Ebay a few weeks ago for a stupidly cheap price(I think $20 or $25), and I'm still mad at myself for not trying harder to win it. The 2MX is a HOT card, and in fact the stock Cube version had a massive heatsink that covered about 3/4 of the card area. I suggest using a base fan with it at a minimum if you want to use this card. The 7500 runs a bit cooler in my experience, although the one that came BTO in the Cube had a fan. The Geforce 3 has a fan also.
The Geforce 3 was never a BTO option, but is the best "drop in" official Apple card that will fit a Cube. I have one in my most used Cube(it also has an 800mhz/2mbL3 Sonnet) and it's fantastic. I'm not a big gamer, but have been trying to "tax" it lately with some GPU intensive games and this afternoon was playing Return to Wolfenstein. I was running OS 9(where this card really shines anyway) and cranked all the graphics settings all the way up without it missing a beat. Admittedly I was only driving the 1024x768 15" ADC display, but still. One of these days, I'll try it out either on the ADC CRT(which can do a stunning 1600x1200, and at a respectable refresh rate using a good GPU) or a 23" ADC Cinema.
When it rains, it pours, and I was actually able to find two Geforce 3s(with the help of
@LightBulbFun) within a week of each other after looking for one for nearly a year. One had a cheap purchase price but ended up costing me a fair bit more since I had it shipped to him in the UK and he sent it on to me(after playing with it
). The second cost me a 256gb SSD.