The rebuilt FA's (four of them) could MU with each other or with the GP-9's and other road switchers of this period. They
could also MU with the rebuilt RS-3's. The FL-9's have no means for effecting manual transition on trailing units and thus
if a rebuilt FA was to have MU'd with an FL-9, the FA would have had to lead. I don't recall of any actual occurance of an FA
and FL-9 in MU operation.