42391 TRF421X Upper Deck Spare 3404174 - Tamiya  [3404174]

Upper deck function on TRF421X

This upper deck is offered as a spare part identified by code 42391 for the TRF421X chassis series. It fits the upper mainplate position and is intended for replacement during repairs or for changing chassis flex and balance as part of tune-up procedures.

The component is produced to align with the TRF421X original mounting pattern and will mate with the existing standoffs and fasteners without requiring chassis modification. During replacement, check that holes line up and that screw lengths are appropriate to preserve the chassis geometry and prevent binding or unwanted play.

As a hop-up or spare, the deck primarily contributes to structure and handling adjustments: swapping decks can change fore/aft stiffness and can be used to refine traction and steering. Retain any original screws and shims removed during the change to keep setup consistency.

Fitment confirmation

Compatible with 42391 TRF421X as shown by the part code and product listing.

A recommended option for mechanics and hobbyists needing a like-for-like spare or experimenting with deck stiffness; installs into the TRF421X platform without needing chassis changes.