[AT] Ford Tractor serial #'s

[D8RMAN at aol.com]

Can anyone tell me if this is a 9N serial#? (Serial #     9N53b7I    Can't 
tell if that b is a 6...Look's like there may have  been another digit at the 
end.) This is for my father's tractor and my brother  sent me these #'s as I 
want to get my father a set of running boards for his  tractor as he is not 
getting any younger and I want it to be easier for him to  get on and off his 
tractor safetly. Thanks for the help. Willard  Smith