The PTO assembly begins with this type of yoke. It is connected to the tractor and then used to attach the driveline. There are two main types of tractor yokes. The first type is a spring-lok, which uses a spring-loaded collar to attach and release the yoke and the second type is a quick disconnect, which uses a push-pin mechanism for connectivity. The tractor yoke can also be designated as 6-spline, 20-spline or 21-spline representing how it matches to the connection on the tractor. Add to Favorite Sellers. Weasler 1-3/4 20 Spline Tractor Safety Slide Lock Yoke 2400 Series. This item is in the category “Business & Industrial\Heavy Equipment, Parts & Attachments\Heavy Equipment Attachments\Other Heavy Equipment Attachments”. The seller is “farmerbobsparts” and is located in this country: US. This item can be shipped to United States.