By the old color, do you mean the Grinch being a sort of olive color instead of bright green? From what I gather, that may not have been accurate - I have heard that the old home video transfers were sourced from a fading interpositive.
Here's a clip from a 1983 CBS airing, pre-home video: http://www.youtube.com/watch?v=QoUhnGNuxJ0
But yeah, mono replacement sucks.