First, review Tom Madden's "The Pullman Project" spreadsheets at
www.pullmanproject.com to see what plans New Haven had. Then go to a reference site such as The Pullman Collection at collections.carli.illinois.edu/cdm/landingpage/collection/nby_pullman to get the engineering drawings, and also review the print literature available at the NHRHTA (nhrhta.org). Also acquire any number of the various New Haven passenger car photo books that are available, or check back issues of ShoreLiner for heavyweight articles. A railroad photo dealer such as Bob's Photos, which usually is present at the Springfield show every January, will have photos of the prototypes. You also can review the extensive collection of NYNH&H data located at the Dodd Library at UConn, which requires an on-site visit to really take advantage of the research material present.
There's no one source that holds the information. You have to seek it out.