Paul,
All my Maunsell moguls have detail differences, the two N's show right-hand and left-hand drives examples plus original and rebuilt frames. The U is one of the few built new and fitted with 3500 gallon tenders. The rebuilt Rivers also ran with the smaller tender but the cab is different and as yet no one makes an appropriate kit. The U1 is a right mix, it started life as an Ace N1 - yes those kits - but modified with 6ft wheels and a 4000 gallon tender. Since then it has been substantially rebuilt with David Andrews U class frames, boiler, firebox and fittings, the valve gear has been entirely replaced using parts from Sans Pareil. Their W class kit had sufficient parts to make up a complete set of the appropriate side rods, connecting rods and all the valve gear. The K is also from the Ace stable and until someone brings out a decent kit it has to do.
Here are a couple more shots
Roger