Hi Ken,
To answer your question, Aristo did buy out most of the Delton molds, but that was mostly the plastic parts. Their brass dome tops and rings are all new at Aristo and not Delton (I actually prefer the profiles of the Aristo Turnings over the Delton ones too!), other parts have been re-tooled in plastic at Aristo, such as the modern pilot, air compressors on the modern C-16 and dynamo, which had formerly been brass castings, other tools were lost completely like the original long pilot.
Kalamazoo also re-tooled their 4-4-0 during the last year of Delton's operation, and with a partnership agreement were going to use C-16 cabs and domes on their 4-4-0...then Delton went bust and the revised 4-4-0s were never anything more than prototypes at Kalamazoo. When Hartland took over Kalamazoo they aquired the 4-4-0 tooling, which had been updated, but lacked domes and cab...and set about making their own. Thats why the Hartland cab is strikingly similar to the C-16 in overal proportions and the domes are very close to the original Delton versions, including the modern rounded domes.
You can also call Navin at Aristo parts and see about getting the Ariso sand dome. Like I said, for the C-16, I like the profile of the Aristo sand dome more. The Hartland version is much close to Original delton, but not as close to the actual Baldwin profile.
David.