Tamiya 3451583 - Lower Bulkhead (42391 TRF421X) replacement lower bulkhead  [3451583]

Lower bulkhead function and fit

This Tamiya replacement lower bulkhead is an RC-scale spare designed to fit the TRF421X homologation line where the original part number 42391 is used. Its role is structural: it locates lower suspension mount points and helps retain drivetrain components inside the chassis layout. The description focuses on compatibility and practical workshop use rather than marketing claims.

For hobbyists maintaining or tuning a TRF421X-based touring car, the lower bulkhead is a common wear or impact replacement item. When assessing fit, verify the 42391 reference and alignment points against your existing chassis before final fastener torqueing. The part supports chassis geometry consistency which can affect handling and setup repeatability.