... such as visible bolt heads on the frames - and I see he's now added some to the bogie sides too, all totally unnecessary if the pivot ran through a tube between the frames. Sorry, but these kits make me very grumpy, and I can't understand why they're so well regarded. This is not to take anything away from your work, which is very neat.
I haven't built the G5 (he couldn't supply photos of the built kit so I didn't buy one), but I learnt some lessons the hard way on his C15 and C16. I agree that his chassis go together well (albeit with silly screw heads), but the problem is that lulled me into a false sense of security for the body, which on both the C15 and C16 was a nightmare - like building a test etch. What I'd recommend is that you check all parts first with a vernier, and lay similar parts on top of each other to check for symmetry (left-hand and right-hand cab/tank sides, and cab front and rear). The cabside aperture was a different width on each side on the C16, something I only found out once I had the the loco nearly finished and was putting the seat boxes in the cab - why was one closer to the aperture than the other? On both kits there was also a silly webbing system to go inside the tanks, which apart from being a solution in search of a problem (tanks on kits have been holding themselves up for decades without the need for such supports) was too high for the outer tank skin, and lifted the tanks up off the footplate. And don't get me started on the castings! I note he's only doing the late s.box door for the G5 so you might want to check your prototype. I may be able to help if you need the earlier flatter one...
I'm also not sure how that arrangement on the bogie and rear frames is going to work, especially when running bunker first - how will the bogie know whether it's its turn to turn, or the frames' turn to turn? And how's the rear frame going to know when to stand down and return to first positions? I suspect that what's going to happen is that it will scoot along straight track at an angle as there is no spring to return it to centre - this was certainly the case with the C15. It's going to be very difficult to get the bolts on the link between main frames and rear frames tight enough and not too tight, as it looks like, as on the NBR Atlantic tanks, the bolts are not partially but fully threaded and running through bolts on both components. If your curves allow it, I'd find some way of locking the rear-frame swivel function out of action - after all, the LRM kit never needed this feature. Or maybe locking it at one end only, so that it does actually swivel and not do a "parallelogram swivel", for want of a better term. But try it first - I may be wrong; I certainly hope it works as you've built it. It might also be possible to rig up some sort of spring attached to the main frames and running through a handrail knob inside the rear frames, so that the latter are under some resistance, and don't start to swivel until the bogie has reached the end of its tether, and also return to centre when back on straight track.
