I have a EZ kit ... I thought of adding a few more pieces on the ends of the coach like electrical connection and water supply fittings to the loos. I'm on the lookout for some good reference books now!
We have bought these parts for our EZ Mk.1s:-
* RCH lighting connectors from JLTRT;
* Regulator cradle, regulator and lamp resistance box from JLTRT;
* Fusebox (the item with loads of wires out of the back face;
* Emergency brake gear / passenger control valve from CPL.
I am expecting to fit JLTRT water fillers to the EZ roof... and the jury is still out on which vacuum cylinder to use.
If you are modelling a carriage with dual heat then you can get the ETH connectors from JLTRT - supplied with the Mk.2 kits.
The sole reference book for details of Mk.1 design and build is "BR Mark One Carriages" (K Parkin, pub. HMRS) plus the supplement. Hugh Longworth has authored a book about the design types / Lots / running numbers, this book extends the history of the HMRS tome. You shall find lots of photos of Mk.1s in the WT Gallery and there is a topic devoted to the
modelling of Mk.1s.