I just got this off da bay. I did a tear down today to see what all is missing, and I noticed a few interesting things. The steam chest is part number 1662/ But is is different from the steamchest that I swapped out (due to zinc pest) on my 1662,m and the one Dennis Holler sent me, both numbered 1662. The one (and the replacement chest from 1662 both have the crosshead guides riveted on, while the one that came with 1656 is screwed on. I supposed these could have been changed. The original chest on my 1662 has slots in the guides, while the one from Dennis and the one with 1656 are solid.
And 1656 has nickel tires on one side, but none on the other. I measured the rims, and both sides are the same size (measured on the inside of the nickel tires, and one of the tireless drives has plenty of marks on it, so I suppose the tires were pryed off, or the two drivers were swapped)
The steamchest on 1656 was held on with none factory screws, so it may not be the original chest. But at least the motor runs!