IIRC Bob Smaus used the Front Range 50' DD welded car for the 1960s
era ACF built SP B-70-14 series of lumber cars with yellow
door(220000-220499). There was a article in the May 1989 RMC.
Not sure how accurate these kitbashes are.
According to the article, these were apparently patterned after
NP#6000-7899 series cars, so they may be a potential project as well
(someone more knowledgable may want to chime in).
Smaus also used the 40' riveted, deep sill FR car with a new 10' door
for the lumber car rebuilds with the famous yellow diagonal stripe
(apparently various number series from 172000 to 189999.
Tony Thompson probably could provide better information.
Hope that helps some...
Duncan BC Canada