Nelson and Group-
Any manufacturer or importer doing new tooling for a stock car would be well served to select the SM-18.
All the stock cars done (with the exception of the Mather car) are prototype-specific if they are not a complete foobie or copy of a copy of a copy of some poorly rendered original tooling which, unfortunately, abound in HO and were also copied to N Scale and then recopied several times.
The Burlington car has the distinct advantage of having rather good published plans and is a car that has a “railroad” look to it. It was in use for a long time (nearly identical SM-16 cars were built in 1922) and lasted into the BN era.
Yes, the SM-19 would also be a good choice and it has good drawings as well. I have not researched what other railroads used the AAR recommended practice design but I suspect there were several major ones.
The SM-19 family has three different roofs (radial metal covered wood, Stanray straight panel and Stanray diagonal panel) and two different ends (wood with external metal bracing and Dredmaught stamped). The sides changed on the SM-19B to flat end braces as well.
I would suggest a range of inserts to accomplish the different CB&Q cars and other prototypes be researched and tooled. The market doesn’t react well to “generic” products and if approached as a project could yield a number of correct, different-looking cars that would cover an number of different roads.
Burlington Bulletin No. 25 is an excellent resource for these cars.
Charlie Vlk