Gaya CDO gives better and PoHed coaches to Mahabodhi and old coaches to 12389/90 Gaya-Chennai Weekly SF. Most probably this rake belongs to 12389/90 which is running with old coaches. Both having RSA, so Mahabodhi runs with this old rake once in a week.
Btw passengers have nothing to do with the outside look, red colour of old coaches fade away with time. Inner maintenance should be proper.