Can't speak to the Bachmann unit but do know about the old-tooling Atlas S2 which if I am not mistaken shares the same carbody as an S4. The LM2 does not fit inside the hood or cab. It is too wide and there isn't sufficient thickness of the hood shell to grind enough width. The module does just barely fit in the hood above the rear flywheel if the module plastic case is removed which can potentially create problems. Also, about .050" needs milled from the flywheel for vertical clearance of the case-less module.
