Slip Clutch PTO Shaft for Most 5' and 6' Rotary Mowers Medium/heavy series 4 pto shaft with 2 disc slip clutch 1 3/8" 6 splined (540) on the tractor end 1-3/8" 6 splined with slip clutch w/ tapered wedge bolt to secure to the shaft Minimum working length is 43.2" Maximum working length is 58.75