I do not think it is a custom...
Though I have never seen this variant, I do not think it is a faded green version either...its colors are even and smooth, and it's overall appearance is sharp and clean.
It looks factory to me. With the accumulated knowledge of all our individual mental indexes of info from the thousands of trains and lots that we've seen, I would have to say that this is VERY rare, and belongs to yet another unknown set, or is quite possibly the prototype coach to the original Mighty Mac prototype!?!?
Either way, at this point it is a one of a kind find!!
Congratulations!!!
Though I have never seen this variant, I do not think it is a faded green version either...its colors are even and smooth, and it's overall appearance is sharp and clean.
It looks factory to me. With the accumulated knowledge of all our individual mental indexes of info from the thousands of trains and lots that we've seen, I would have to say that this is VERY rare, and belongs to yet another unknown set, or is quite possibly the prototype coach to the original Mighty Mac prototype!?!?
Either way, at this point it is a one of a kind find!!

Congratulations!!!

Play nice & have fun!!
