This is definitely a Troy-bilt model number. Unfortunately, it doesn't show up in any of the parts finder systems either. Are you 100% sure you're reading the model number correctly? It's numerically close to the blower for the GTX garden tractors so its probably just slightly newer and would be for one of the pre-MTD TB lawn tractors. I seriously doubt it would be a direct fit on a newer MTD built TB. MTD's manuals site actually does cover most of the GardenWay built stuff, even though it predates MTD's ownership.
ok my dad has 2 mtds one he bought new and other he bought from my grandparents neighbors for 20 dollars lol. both run and drive. one he bought new is a 17.5 hp briggs yard machines gold model 13ad698g300 serial 1k272b30118. one he bought for 20 dollars is a 2001 yard machine 17hp briggs twin, model 13bk6089129 serial 1c071h20020. now this one looks like it take a cub deck lol. my bet is on the 2001 if it does fit one of the 2. and here are pictures of the blower attachment. there is some brackets i have that are not pictured. wish mtd made troy-bilt stuff through out the whole time would be alot easier :banghead3