So, my old JCM 800 cab is missing the logo, I was if it would be worth replacing, and where I could buy a replacement for a reasonable price, since I don't want to drop a king's ransom on a piece of plastic.

Also, what measurement would fit it best? (I'm away from home, so I can't check physically)

Hmm, I have the feeling that Marshall might be the kind of company who would be too fat and lazy to do it. Who knows, they may surprise me. I'll give it a try.