Thanks Max,
I found one photo of the Mexican Central on the Searles Valley historical society webpage, it shows cars which may be the same as the one behind the engine at Knott's. I am now curious about digging through the abandoned lime pile, though I would bet that Kerr McGee has little interest in unearthing the pile, now that they got the EPA to say that it is exempt from mitigation - I think - from what I read online. I am curious if a locomotive buried in lime waste would be in restorable condition (that is, if it were to exist). I guess it depends on how much water would be flushing the pile and the PH of the lime. If it were like calcified lime and had a PH of 12 or above it should be in excellent condition, per the below explanation of rust in alkaline conditions:
Corrosion of embedded metals
Searles Valley Historical Society