Ok, so nipping back to Court for a moment…
What we do know is that there isn’t really much of a standard thing as a GW tender. The only tenders that definitely always had the same type of tank and frame during their life are the Hawksworth ones behind the Counties which were 6″ wider than all the others.
Apart from that, the tenders were like the London Routemaster, entering the works the tank and chassis were separated and overhauled at different rates so what then came back out was almost certainly different.
And so it was I noticed that a number of Collett 3500 gal tenders ended up with Dean chassis. I also noticed the Collett 3500 tank bore a striking resemblance to a Dean 3500 with an added raised lip around the tank filler area.
Thus, for my Saint, all I had to do was add the raised Collett feature and I had a passable Collett 3500 tender using the original one that came with the Saint model which saves messing about with fitting a new body to the tender drive.