I work for Trane now, but haven't dealt with this issue too often. Your best bet would probably be to contact your local Trane office and speak to the Literature Coordinator. There's someone at each sales office who is in charge of ordering IOMs and specific technical manuals for all kinds of Trane units. These manuals may contain proprietary information, and if they are available for sale to non-Trane contractors (depending on the manual, they might not be allowed to sell them to outside contractors), will probably not be cheap.