I have a couple of these 3-rail MTH auto cars with end doors. They made a variety of these, I got elder versions with cast on grab irons oversized ladders and monster stirrups. But I love the rest of the car, it makes a very good and inexpensive representation of a Union Pacific A-50-15 of 1938. The underframe, however, is a mess and a conversion only became an option since I have a 3D printer.
Here you can see the printed bolster in place. I had to file down the car ends a bit to end up with the coupler in the right hight in relation to the riding hight. The geometry here is essential for a good appearence. But once you got the work done, you can convert easily as many cars of the same type as you wish.
The new truck bolster has a big cone to accomodate the metal underside of the car. Next time I will work on lowering the underbody details somewhat more, they sit too high up there. The car has an odd assembly philosophy. Here's the PLA printed bolster. I work in FUSION 360 (free).
The ladders were really a problem and so I desided to solder new ones. A good exercise since I don't soler a lot.
The new ladders look much better, although I made a mistake in placeing them in a different stepping hight. Next time!
Tamiya grey rattle can primer is what I use all the time on plastic.
Followed by some Tamiya brown/red. The color sprays good when I thin it about half with alcohol. These grab irons were left overs from a InterMountain reefer kit, with two of these you end up with enough spare grab irons for an other car.
I did a big mess when I tried to sand away the original MTH factory lettering. The damage was repaired with some putty and a bit of rust. In the end it turned out even better than without. Protocraft decals went on, I enjoy lettering stuff a lot.
I've discovered Tru-Color and Mr. Metal Surfacer for painting steel wheels. Absolutely my favorite color! it layes down super smooth and it does not take on powders, so mooth it is. I think this would be perfect to do decalling on. Will experiment more with it in the future.
These are InterMountain plastic trucks converted to P:48 with a printed truck bolster. I work on it but the results are promising.
The weathering might be a bit over done and was carried out with oil washes on super flat varnish. Here I have much to learn. The kind of clear coat extremely affects all weathering effects.
Would I buy more of these? I've got a total of four and I will convert them but maybe I'd rather save some money and go for a Protocraft brass model that is absolutely 100% super correct. But hey - it was fun and that car certainly is one of my babes now, nursed back to health.