Very specifically, the 1973 made-for-tv version of Miracle on 34th Street, with Sebastian Cabbot (Santa), David Hartman (Generic White Male), Jim Backus (Hapless Flustered Stuttering Management) and Roddy McDowall (as the "store psychiatrist").

This is admittedly tough, as it is not currently available anywhere I can find, so you would have to secure rights to use the film itself, as a "riffs only" release would not work. Also, it is in 4:3, and I know you guys tend to like the 16:9 stuff for RiffTrax, and you aren't likely to get a new transfer from film, so it's going to be crummy NTSC broadcast-ready video, even more likely an interlaced DVD or VHS at best, like what you probably had to work with on MST3K.