OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Model 450407 Want to get this SB45 up and running

Hey I found a motor off a Model 45 No. 15953 but it doesn't have a Tag on the motor the guy said it was a 17"
So that would mean it's a bigger motor... will I be able to use it for parts ?

What is the difference between the sizes ?
Piston, stroke , bore ?

Pictures from the seller