As part of my searching for information on the DTRs and DLRs, I looked up the FCC Type Acceptance information on the FCC’s website. My curiosity was piqued given that it’s directly related to my line of work as an Electromagnetic Compatibility (EMC) Engineer plus it appeals to the amateur (ham) radio operator in me. I normally look up the FCC Type Acceptance information on all of my radios. 
Not all documents submitted to the FCC are publicly viewable such as schematic and tune up information as they are considered trade secret information and on permanent confidentiality with the FCC. Some documents may have been on short term confidentiality which has long since expired and are now viewable. Other documents such as the Owner’s Guide and external photos have been publicly viewable from day one after being submitted to the FCC.
DTR FCC Type Acceptance information:
The Gen2 DTR550 and DTR650 are type accepted under FCC ID: AZ489FT5852
The Gen1 DTRs are type accepted under FCC ID: AZ489FT5842
DTR Gen2 FCC information:
https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=pgyeO9Mz1dE9DgP2PP2ZmQ%3D%3D&fcc_id=AZ489FT5852
DTR Gen1 FCC information:
https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=rtrwyiY%2FykY6QXe3FH6emg%3D%3D&fcc_id=AZ489FT5842
Gen1 documentation submitted to the FCC includes references to the old MOTOTALK name, before the DTR product name was coined. Some of the correspondence back and forth between Motorola’s EMC test lab and the TCB (Telecommunications Certification Body) is interesting.
DLR FCC Type Acceptance information:
There are 2 sets of FCC type acceptance data listed for the DLRs. The DLRs are type accepted under FCC ID: AZ489FT5870
DLR 1 of 2: Exhibits cover intentional radiator (transmitter) certification testing.
https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=qOf3zYjvF%2FRtmsEJ8QNtoA%3D%3D&fcc_id=AZ489FT5870
DLR 2 of 2: Exhibits cover unintentional emissions (radiated and conducted) testing. The power supply in the MUC seems to be a little bit noisy below 30MHz.
https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=bzVPyVfiOna6gzLPIVXpOQ%3D%3D&fcc_id=AZ489FT5870