An assembly connects a pitman arm to a slot in a crank arm of a pumping unit. A pin extends from the pitman arm disposed on a first side of the crank arm. The pin is disposed in the slot of the crank arm and has a distal end exposed on a second side of the crank arm. The distal end defines an external shouldered profile. A clamp is positioned on the distal end of the pin. The clamp has an internal shouldered profile, which is configured to engage the external shouldered profile on the pin. One or more spacers are disposed on the clamp and are configured to adjustably extend from the clamp toward the second side of the crank arm.