1. Most axles have an identification tag with the axle capacity and axle diameter.
2. Measure the axle diameter or circumference.
Shock Kit Axle Diameter Axle Circumference
2450
2 3/8" Approx. 7.5"
2460
3" Approx. 9.5"
2470
3.5" Approx. 11"
3. Contact the RV manufacturer. They can decode your VIN to determine axle diameter and capacity.