Looks like a model 416A, made from mid 50's until very early 60's. They were sold to mate up with John Deere 40/420/430/435's, 50/520/530's and any other simular powered 3-point tractors of the day. By more modern standards, that plow doesn't have a lot of throat clearance, making it tend to plug in heavy sod or weedy/trashy conditions. Most wear parts are still available (through aftermarket sources) Landslides are hard to come by though.