I have just bought my first two DCC ready steam locos after having mixed results on 5 conversions. The new stock are Hornby R2459 GWR 4-6-0 Castle Class "Wellington" and Bachmann 32-003 Blue Riband Steam GWR 4-6-0 Hall Class "Kinlet Hall". Much to my surprise, neither had any information on fitting decoders. Hornby had a small slip stating that the DCC unit should not be operated without the (supplied) insulation sleeve being in place. (The leaflet with the Bachmann E-Z Command decoders - 36-551 - I intended using stated "never wrap the decoder in insulating tape! Who do you believe?)
I fitted a decoder to the Hornby first. Once I had realised removal of the forward weight made room for the decoder it was quite straightforward as the decoder slid into the spot left by removal of the weight. Once programmed, the loco runs well.
The Bachmann was a very different kettle of fish! On taking the body apart, I was shocked to see absolutely no room for the decoder. I went looking on the Bachmann website for some guidance. On the page "Fitting Decoders to Bachmann locos" the first thing I noticed was the statement 'We are not able to recommend a decoder for each locomotive...' - amazing given that they market decoders!!
Further down the page you find some info on fitting. Under Blue Riband Steam they say 'Those with a space and decoder socket present no problems. Remove body, fit decoder and replace body. A popular approach on other locomotives is to completely remove the factory fitted circuit board as it's not needed for DCC and use the space to fit a small decoder. Otherwise, locate the decoder in the tender."
Removing the circuit board would not leave room for the Bachmann decoder and fitting it in the tender requires a small hole to be cut in the tender base. I am very reluctant to proceed further at this stage for fear of breaching warranty and have sent an Email to them requesting advice on fitting a decoder. I'll keep you posted on progress.