They ended up with the huge collection of OEM manuals the NRI had, when that school was shut down by McGraw-Hill. I once asked about information on a 1938 Philco tombstone radio from NRI, and they mailed me an original service manual for free, since I had taken a course at one time.
Sams only reverse engineered items that sold in excess of 20 thousand units, but they collected OEM data on everything they could get their hands on. They also wrote manuals for some company's products that didn't meet the 20K unit minimum. Those were only available from the OEMs.