The chassis unit when available was part 35-300. You never know, some retailers may still have one, even though Bach discontinued it years ago. The split chassis (apart from the motor which appears to have eternal life) is a pretty short life unit, but if the axle muff has fallen apart, thorough degreasing and careful reassembly with Araldite can restore function. Eventually though the plating wears off the half axles, chassis journals, and tyres; and consequently electrical pick up becomes hopelessly impaired, and the scrap line beckons...