This pair of leaf spring center pins from ORV Suspension have a 5/16-inch shaft diameter and is 2.5-inches long.
Leaf Spring Center Pins, 2.50 Inches Long, 5/16 In
Are you rearching, modifying or restoring your leaf springs? Don't reuse the old centering pins when reassembling your leaf springs! Over time rust and stress fatigue the original hardware leaving it susceptible to failures. The last thing you want is for your leafs to come apart when you are headed down the road.