Installation Instructions on the ITHACA 37  M & P Model Plastic Forend Grip
The objective is to remove the pump handle/slide bar assembly off of the weapon. This will allow you to unscrew the end cap and replace the wood with the plastic
  1. Remove the barrel from the weapon.
  2. Unscrew the magazine cap, CAUTION:  The magazine spring may jump out.
  3. Take the screw completely out of the barrel support bracket and slide the bracket off the end of the magazine tube.
  4. Notice on the bottom of the breech bolt there is a spring loaded pin that locks the breech bolt to the pump grip/slide bar assembly. The lock pin has a groove in it for a sharp point tool. Push the pin away from the slide bar and pull the pump handle forward and off the end of the gun.
  5. Once the pump handle is removed, it is easy to unscrew the end cap with the flat steel key and replace the wood forend.
  6. To reassemble,  reverse the above action.

CAUTION: Do not put any pressure on the slide bar. it will bend and then bind up inside the receiver