I'd be interested to see what the OP is referring to as well. Other than the no. 34635 mentioned above, I've never seen any other Lionel Legacy Santa Fe blue freight scheme F units, and I've been watching. I passed on the 34635 set because I didn't like the black roofs. If they'd done the engines with blue roofs, I would have jumped on them.
Interesting that PRREnola mentioned his Revell H.O. Santa Fe F7. I had (and still have) that same engine, received as a Christmas present in the later 50s (along with its set). It always bugged me that it came with only a single F7, and not an A-A set. A number of years ago I got the Lionel traditional Santa Fe blue F3 set with the A-A, and also added TMCC to them (picture below). Felt good to finally get an A-A set!