a little discussion on MTH's 1st generation of this model and the differences between them.
The PS3 is the third generation/offering of this engine. The first generation (PS-1) didn't have the black grills. Prototypically they turned black from getting dirty. Also, the PS-1 version was missing the builder plate. I was fortunate enough to get one from candoplates.com while they were still in business. There was also an issue with the spring on the front pilot. I assume that that was resolved on the second generation. JDS did the PS-2 conversion. Mine is now a great runner.
I really have to hand it to MTH for making this model. In today's environment, I can't imagine this as a new offering. As for size, it is a beast. There's serious overhang even on 0138 curves.