There are several decoders available pre-fitted with a 6 pin decoder socket. The standard is NEM651, and is described in the linked NMRA RP9.1.1 document.

We have used the Digitrax DZ125IN decoder in these sockets. If you want to use a decoder that only has wire connections it is possible to get a plug and wire it to the decoder. DCC Supplies sell a suitable plug.

The plug needs to have the following mechanical properties

The connections are as follows:

Pin
Colour
Function
1
Orange
Motor Right
2
Grey
Motor Left
3
Red
Rail right
4
Black
Rail left
5
White
Front headlight
6
Yellow
Rear Headlight