Air Conditioner ID

When we got our #179 last fall, we sent off the warranty papers.  Problem was, we couldn't find the model number and serial number on the 13500 BTU Dometic AC.  I think it's a Penguin  2.  When I sent off the original warranty papers, I indicated I couldn't find those numbers.  Last week, we got a letter saying we had to send them. 

I see some online Dometic factory sites devoted to awnings, ACs, refrigerators, etc., but no phone numbers.  There was a site to chat online with a Dometic technician.  When I explained the problem, the response was to ask if it was worth $19.  I closed out that chat. 

The letter says the numbers are up top, under the AC shroud.  I'm 75 and I looked up there once but I've had spinal fusion and I'm very reluctant go go again, especially if I have to take off the shroud. 

The letter also says the numbers are also on a data tag on the bottom of the AC.  They added

"To locate the data tag on the bottom of the air conditioner, open the filter door on the ceiling air box directly below your air conditioner and look through the opening with a flashlight to the bottom of the air conditioner.  If your air conditioner also contains a relay box, you will need to look past this box as we to the bottom of the air conditioner." 

There are two filters and they slide out - no "door" that I can find.  I have removed the filters and peered through with a flashlight.  No numbers are obvious.  For that matter, I can't tell if there is a relay box.  Has anyone else had this problem?  It seems like it shouldn't be hard to find required information, but so far - nothing.