Park your John Deere mower on a level surface to access the mower deck properly. Turn the mower off.
Pull up on the lift lever on the right side of the John Deere's driver seat and raise to the highest possible position.
Position the mid-mount mower deck under the center of the John Deere mower, so it is evenly spaced along the base of the mower. Lower the lift lever back down to its lowest position.
Move to the front of the deck and lift it up to the bottom of the John Deere mower. Find the two pin slots on the deck's front. There will be one on each side. Insert one of the included deck pins into each of these slots. Secure each pin in its place using one of the spring retainer clips.
Position and attach the included deck's suspension arms by sliding each into the brackets at the deck's rear. Each of these arms also must be secured with a spring retainer clip.
Locate the anti-sway bar. This is the remaining bar that is already connected to the deck and extends from its center, in front of the deck's suspension arms. Slide the sway-bar into the rectangular chassis bracket found at the center of the mower's base. Apply another spring retainer clip to set the bar into place.
Insert the two side pins into the sides of the mid-mower deck. Secure each pin with a spring retainer clip as before.
Find the pin slot beside the clutch gauge on the bottom of the deck. Insert a pin here and secure it with another spring retainer clip.
Insert the last pin into the pin slot under the John Deere's throttle. The throttle is near the back of the mid mower deck. Secure this pin with the final retainer spring retainer clip.