For the best.... there are two: TM and Carter and Gruenwald. Both are site sponsors and both are extremely knowledgeable about Cubs. There are several advantages to dealing with either, the parts ARE for a Cub and OEM quality.
Stuff from TM will get to me in 2 days! If it doesn't meet his high standards, he won't sell it PERIOD.
One of the parts guys at C&G is Ken Updike and he wrote the book, so to speak:
Farmall Cub & Cub Cadet (Farm Tractor Color History)
1971 Cub (Rufus) 1950 Cub (Cathy) 1965 Lo Boy Fast Hitch (Nameless III) 1970 Cub 1000 Loader & Fast Hitch (Lee)