Walla Siding on Christmas Day 2008, BHP Billiton Electro-Motive built SD70ACe mid train unit 4324 serial 20066862-037, this is the 'class leader' of a batch of ten SD70ACe units built for BNSF but sold to BHP Billiton following construction. Note the difference of this cab shot to the one of lead unit capable 4332.