it's an 8 pin plug...
http://www.atlastrainman.com/HOLoco/tmhogenset.htm
(I personally will be adding a 9-pin adaptor for future sound and ditch light installation...)
you'll want one like this:
http://ncedcc.com/component/virtuem...rden_flypage.tpl&product_id=42&category_id=13
(digitrax doesnt make 8 pin decoders it seems... bummer!!)
Digitrax does make 8-pin decoders in HO, N and Z scale sized decoders.
Here is how the designations work.
D = Digitrax Mobile Decoder
H/N/Z - Scale
1 - decoder series
2/4/6 - number of lighting functions
Suffixes:
IP - Integrated Plug (8-pin plug)
D - Wire harness
P - Wire harness with 8-pin plug
PS - Short wire harness with 8-pin plug
For example, DH123P = An HO scale decoder with 2 functions with a wiring harness that has an 8-pin plug. These decoders have a harness to make it easier to install. The 8-pin plug is for locos with the socket, and if you take the harness off, you get the 9-pin for Athearn locos.
DH165IP = An HO scale decoder with 6 functions with an integrated 8-pin plug and no harness.
If your road has flashing ditch lights, DO NOT, I repeat, DO NOT use a digitrax decoder with a locomotive with LED ditch lights. Digitrax decoders are still in the stone age and do not have an LED compensation mode. The LEDs will slightly dim then go back to full brightness and will not flash.