John B., WELCOME!
You'll get all sorts of answers to the question of "Which Cub to get?" I'm partial to the narrow frame models, especially the 125. But I'll recommend the wide frame model 149. Now which deck fits which tractor isn't a real easy question to answer as the sub-frame can be mixed and matched somewhat which can blur the answer. As a quick and dirty, but not entirely correct answer, 36", 42" and 48" decks fit narrow frame Cub Cadets, and 44" and 50" decks fit wide frame Cub Cadets. Now with the proper sub-frame a 36" or 42" deck can fit the wide frame Cub Cadets. If you're not sure which are narrow frame and which are wide frame Cub Cadets let us know and we'll let you know.
You'll get all sorts of answers to the question of "Which Cub to get?" I'm partial to the narrow frame models, especially the 125. But I'll recommend the wide frame model 149. Now which deck fits which tractor isn't a real easy question to answer as the sub-frame can be mixed and matched somewhat which can blur the answer. As a quick and dirty, but not entirely correct answer, 36", 42" and 48" decks fit narrow frame Cub Cadets, and 44" and 50" decks fit wide frame Cub Cadets. Now with the proper sub-frame a 36" or 42" deck can fit the wide frame Cub Cadets. If you're not sure which are narrow frame and which are wide frame Cub Cadets let us know and we'll let you know.