I purchased these drawings from the Museum of Transportation in St Louis, MO. They have most or all of the ACF passenger car blueprints.
The ACF blueprints refer to points of the compass, which I've never seen anywhere else. Here is the translation:
Note: Several drawing have numbers like U-32059-B, U-31151 or R-31470A. These identify individual pieces of steel used to fabricate the carbody, and are also found (with an occasional error) in the Bill of Materials. The prefix is a mnemonic (U=underframe, R=Roof) and the suffix distinguishes identical pieces. Purchased components are usually idenitfied by Make and Model number.
