oldelmer1,
Get your part number out and check it against these charts. Also, you have to determine if you need 'severe service'.
I would call the weight we have severe, so you might need these baby's. If you have any doubt, or questions call these guys, they were extremely helpful to me. They actually sent me the correct H.D. Timbrens free, after I bought the lighter duty ones.
Regular service
Severe service or heavy duty