Locogear has some drawings available in 1.5" scale. Some of these are original Lima drawings that have had the dimensions changed to 1.5" scale, some are original Locogear drawings. See Locogear Technical Bulletin #7
Plan Ahead Designs has a set of drawings for the Western Maryland #6. Although this
is a complete set of drawings the author chose to deviate from building a technically
correct model by substituting needle bearings for bushings and redesigning the
truck axles. I have a set of these drawings but would recommend buying the
Locogear drawings and the original Lima drawings.
The Allen County Historical Society has many original drawings for these Shays. Many of the drawings pertain to both Shays. The ACHS is easy to deal with and quick to respond. Drawings are copied and sent in a mailing tube.
The California State Railroad Museum has an extensive collection of original Lima Shay drawings. They will either make copies or scan drawings and burn to a CD. I prefer drawings on CD as I can display them on the computer then print out just the section I am working on and take the smaller drawing into the shop. By having drawings burned to a CD you help the museum make digital copies of their collection which will help protect the drawings from loss.