Steering Arm, Center. PART NO: A-R61159. Replaces R50769 Dim A (1)6 splines. . MODELS: John Deere TRACTOR: 4050 John Deere TRACTOR: 4055 John Deere TRACTOR: 4240 John Deere TRACTOR: 4250 John Deere TRACTOR: 4255 John Deere TRACTOR: 4430 John Deere TRACTOR: 4440 John Deere TRACTOR: 4450 John Deere TRACTOR: 4455.