One product that I have not noted much here in this site yet are the six-wheel trucks sold with the Scale-Craft 4-8-4 and the later version of the 4-6-2.
I used a nice pair of these on the tender of this locomotive (see more at this link) some years back. Then, I had no issues with the trucks other than attaching them to the tender, which I did with flat head screw and a nut up inside the tender. There is no room to screw them on conventionally.
Fast forward to now. I am working on a pair of S-C 4-8-4 models. The one that had been rebuilt by Pierre Bourassa, he actually used brass HO sideframes for a similar truck and worked out his own trucks, which was a great solution to a thorny truck problem.
Thorny problem? Short version of this topic is that S-C tender trucks are always problematic for electrical pickup, and then with this particular six-wheel truck there are yet more issues to work with.
The wiring method recommended by S-C for all their models was to pick up power from the tender trucks only. You were to wire feeders to the bolster clips on both sides of the trucks. The zinc material of the trucks, though, is not a great electrical conductor. On my smaller S-C locomotives I always use Nason trucks with bronze sideframes on the tenders.
There was one other modification this builder made, clearly one end of one sideframe broke off, as in one complete journal box, and he used very small screws and shim brass to repair the sideframe! “The things people did before Facebook.”
Turning to my parts supply and analyzing what I had I found loose parts for five more complete trucks, of which I built up four. One side point to mention is that S-C axles are not all the same length and these trucks will take (and work the best with) the longest of their axles. So I went through my S-C wheelset supply with calipers, and the 12 best of the longest examples are on those two pair of trucks.
To the scale drawings, one thing that you would wonder is how do you attach these trucks to a tender? The answer is with cotter pins. There really is no room to screw anything on, and that is the attachment method used on my complete engine.
Which brings me to now. The next project is taking the trucks on the complete model off and apart to clean them up and get the wheels in gauge. At that point I will analyze their future use. I may replace them with a pair of stock trucks I just assembled from parts (and salvage off the Nason parts to fix a Nason passenger truck), but if I can get them rolling well I will probably leave them as they are.
And now I am ahead one more job, I now have trucks to use on my 4-6-2 project tender.
To close, if you are working on an S-C 4-8-4 or 4-6-2 tender and need some sideframes, I have a lot of them extra, along with some parts for the bolsters, just let me know your needs. Happy to help others get models back in operable shape.