I have two HP82161A Digital Cassette Drives, the color of my first drive serial no. 2230A18882 is very similar to the HP-41 calculator where HP called Ink Brown (I would say it is more of black to my eyes!), the second unit - serial no. 2338A02973 is I guess I would call greenish brown and it is of the same color of my HP82162A Thermal Printer (serial no. 2341S20166)!
I wonder did HP change the color of both the drive and printer from Ink Brown to lighter color. Incidentally, I noticed that both the drive and printer in the picture in HP Series 40 brochure (5953-5557) seems to be Ink Brown (see below)
http://www.geocities.com/wongyapkong/series40.html