Chosen Solution
craftsman riding mower
blueowl072002, the primary drive belt is part number 4866J and it is a 1/2" X 78" belt. The secondary drive belt is part number 6753J which is a 5/8" X 60" belt
I realize this is a very old post but we are talking about a very old Lawn Tractor. I own and am restoring a Sears Craftsman LTV/11 Model# 917.252641 riding lawn mower(Lawn Tractor). The correct answer, based on replacement experience, to the question of Drive belt size is: Primary: Sears part #4866J (Sub: 583768401 or 106729X) It is a 5/8” x 47.5" v-belt Secondary: Sears part #6753J (Sub: 583773201 or 100615N) It is a 1/2" x 56.5" v-belt If a search is done using the Sears part #’s many of the results will be similar 60" and 78" belts mentioned in another answer but a search using the substitution numbers gives more accurate results.
