carl v:

A switch is equipment that does not affect the capacity, stability, or safe operation of the truck. Manufacturer approval is not necessary.

ANSI/ITSDF B56.1-2005, Safety Standard for Low Lift and High Lift Trucks; 4.2 Modifications, Nameplates, Markings, and Capacity:

4.2.1 "Except as provided in para. 4.2.2, no modifications or alterations to a powered industrial truck that may affect the capacity, stability, or safe operation of the truck shall be made without the prior written approval of the original truck manufacturer or its successor thereof. When the truck manufacturer or its successor approves a modification or alteration, appropriate changes shall be made to capacity plates, decals, tags, and operation and maintenance manuals."