Here are the ex-Monon RS-2m dispositions from L&N Diesel Locomotives by Castner, Flanary, & Gordon.
Monon 51 to L&N 260 (2nd) retired 8/23/73 trade in GE.
Monon 52 not renumbered by L&N retired 1/20/72 rebuilt to slug by Railroad Supply to L&N 2063.
Monon 53 not renumbered by L&N retired 6/7/72 trade in GE
Monon 54 not renumbered L&N retired 1/20/72 rebuilt to slug by Railroad Supply to L&N 2064.
Monon 55 not renumbered to L&N retired 3/1/72 trade in to GE.
Monon 56 not renumbered to L&N retired 3/1/72 trade in to GE.
Monon 57 not renumbered to L&N retired 3/1/72 trade in to GE.
Monon 58 not renumbered to L&N retired 8/23/72 trade in to GE.
Monon 59 not renumbered to L&N retired 10/30/71 rebuilt to slug by Railroad Supply to L&N 2065.
My speculation would be that one of the units traded to GE could have found its way to Mexico on a short term lease.
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COTTON BELT: Runs like a Blue Streak!
COTTON BELT: Runs like a Blue Streak!