I have a pair of K-Line brown & orange Illinois Central Alco FAs. I am not sure how rare they are but I've never seen an other set.
In the 90s K-line made several AA sets of these small Alcos, including those ICs you have and also some Northern Pacific Loewy passenger scheme models, primarily to match several baby streamliner passenger car sets Lionel made at that time. Lionel only made some small steam engines to go with their cars. These FA engines are around, but I suspect most people have them with the passenger car sets and they don't come up all that often. These are the Lionel cars they were meant to go with:
I have the passenger cars as well. I also have the K-Line Northern Pacific Alcos and Lionel Passenger cars.