What is inside?
Since no one has stepped forward yet with a like model and answer, another option to calling Atlas is if you can read CV's, checkout CV08 to get the "Manufacturer's Identification" number. Some of the ones I know of are:
Manuf CV08 = Numerical (Hexidecimal)
Digitrax = 129 (0x81)
ESU = 151 (0x97)
Lenz = 99 (0x63)
NCE = 11 (0x0B)
SoundTraxx = 141 (0x8D)
I know Digitrax puts the model number of the decoder in CV07 and I think some of the others do as well, so you may be able to figure it out without prying the engine open. With that information, you should be able to get a manual online that tells you what each CV does and even how to reset the decoder to factory defaults.