Wow David, how lucky can you get!!
I've asked this before... In the '39 catalog, Lionel claims their scale switcher has a "20-to-1 gear reduction." When discussion on the Forum revealed an observed ratio of 14.77, I wondered whether Lionel changed the gearing during early production. I know for a fact they changed the ratio of the 700E (in that case they made it slower.) Are you sure this is a custom job? If Lionel originally used tower gears of 1:1, your worm and worm wheel would yield the gear ratio of 20:1 claimed in the catalog.
From the apparent pitch of the worm, I presume this unique combo of worm and worm wheel are self-locking. Can you turn the worm shaft by turning the geared wheels? Along with possibly being perceived as too slow, if the loco didn't coast freely, that might be another reason why Lionel switched to a taller gear ratio with a multi-threaded worm.
@Steamer @gene maag is that 1615 shell in your photo repowered with a 227-type mechanism, or a 201 / 203 type mechanism? I always thought the 227 "semi-scale" switchers had a longer boiler. The 201 / 203 0-6-0 is a neat engine that was never reissued after the war. I have no doubt that the 203 6-wheel parallel plate chassis would be a drop-in upgrade for a 1615. I've also seen some home-made upgrades using a 1666 or 2026 chassis. Not sure how difficult this mod is, but I've seen it more than once!
