This set was produced to introduce an more comprehensive set for these classes, which hadn't been done by previous manufacturers.
In 1903 the PRR made a major design change in their cabin car fleet by introducing the ND, which had a steel underframe. This class was larger and stronger than all previously made Cabin Cars. In 1916, a few of these ND's received a redesigned underframe allowing for the installing of two four-wheel trucks, creating the NDa class. In 1914 the N6a and N6b classes were introduced. All four of these classes were used extensively across the system through the mid-1950's, when due to age, some of the cars got transferred to MOW service or were scrapped.
This sheet includes enough lettering for the above four classes of cars in their Pre-1954 scheme before they were reapinted with the Shadow Keystone monogram. The HO sheet includes enough data for 4 ND's, 2 NDa's, 2 N6a's and 4 N6b's, plus additional data for many additional Cabin Cars.
All of the above classes have been produced in HO by various brass importers. Additionally, they all have been produced in HO and N kit form by Quality (Gloor) Craft, and resin by F&C (ND and NDa). Walthers also recently produced a RTR version of the N6b.
For references in regards to PRR's Wood Cabin Car fleet, please consult Cabin Cars of the Pennsylvania and Long Island Railroads Caboose Data Book No. 2, published by N.J. International, The Keystone, V6 #4 published by the PRRT&HS and Volumes 1-3 of the PRR Color Guide.