I am, on and off, researching a 9J (J11) to build. I thought I had figured out the tender options - I was wrong! - but now I have noticed something else. As with the Q4s, the presence of an external exhaust pipe along the RH side does not necessarily signify a superheated engine. The early boilers had internal exhaust pipes, but after a certain date external exhaust pipes were fitted. And as boilers were swapped about (a lot) it is impossible to be sure whether or not the model ought to have one unless you have a dated photo showing the RH side.
This warning is probably not relevant to anyone modelling the LNER era or later - you can pretty much assume an external pipe - but for those of us working in the mid to late GC era it's another flipping nightmare. Sadly good photos of 9Js in GC condition are not two a penny. The very early ones are only useful if you are modelling that era. The later ones beg the question as to whether the same boiler was carried at the date being modelled - if not, did the earlier boiler have the external pipe? Yeadon is only of limited assistance - it gives the date of boiler changes - and the RCTS books still less on this matter.
This warning is probably not relevant to anyone modelling the LNER era or later - you can pretty much assume an external pipe - but for those of us working in the mid to late GC era it's another flipping nightmare. Sadly good photos of 9Js in GC condition are not two a penny. The very early ones are only useful if you are modelling that era. The later ones beg the question as to whether the same boiler was carried at the date being modelled - if not, did the earlier boiler have the external pipe? Yeadon is only of limited assistance - it gives the date of boiler changes - and the RCTS books still less on this matter.