Apparently the voice actor for Gen1 Ramhorn (the rhino cassette) has recently died. John Hostetter was (only) 69.

Talk about being signed on to do a single obscure role... I didn't even remember Ramhorn having any lines. If he did, it mustn't have been many.
It seems strange to have someone signed up to just do the one role, and probably only a handful of lines in maybe one episode... when they could just have one of the other voice actors do it while they are there (and probably not cost anything extra).