New precision-designed composite chassis frame with split design has a separate front part and rear chassis plate. Compatible with both XB4 and XB4 2WD. The split design allows the entire rear suspension to be mounted in either standard position using the rear chassis plate, or to be placed lower by mounting the rear suspension directly to the aluminum chassis. The direct mounting of the rear suspension increases traction and is recommended for low-traction tracks; optional rear suspension holders 363311 & 363321 are required.