Lippert acquired Kwikee about a year ago and has been integrating their step product line with Kwikee, so common parts are not surprising. But yours is probably an older model, pre-acquisition?
Are the prices you are comparing from the same source? Pricing differences are common if, for example, one comes from Amazon and the other direct from Lippert. I see Lippert series 42 motor tables on Amazon for $122.
Different model steps have different motor tables (the plate the motor bolts to). Differences may be tiny, e.g. bolt hole pattern or tiny changes of dimensions.