I searched using https://www.google.com to see if anything resulted from an internet search that might be of assistance.

Unfortunately, not very helpful examples of searching internet results shown below, perhaps due to age of equipment:

https://hvac-talk.com/vbb/attachment.php?attachmentid=350031&d=1359153063

http://pts.myrheem.com/docstore/webdocs/servicedocs/histlib/pdfs/Gas_Pack/%5B-%5DRGG/R22-823Rev2.pdf