It looks like I posted this question in the wrong forum. I'm brand new to OGR.
When I saw TINPLATE in the FORUMS list, I took it in the broad sense - underscale toy trains (of any construction) on folded track. Now I see there's a separate HI-RAIL, 027 AND TRADITIONAL 3-RAIL O GAUGE forum. I'm guessing a plastic-loco question belongs in that forum.
I apologize. Please forgive the noob mistake.
-- D