First off, funny but I've intentionally removed the pickup roller you lost accidentally, and my RDC's run through 027 switches with no stalling. And yes, the K-Line RDC dummy units have pickup rollers. Also because parts are getting more expensive, I've removed one motor truck from a couple of my K-Line Budd cars, and replaced them a dummy truck, making them single motored units. But since I usually run them a just a single unit, or with just one dummy, the single motor works fine.
Okay, Brasseur's bought out K-Line's entire inventory of parts. I did a search for you, so the link below shows the RDC parts available.
https://traindoctor.com/index....&dfrom=&dto=
Now I should note that the same motor truck assembly for the RDC is also used for the K-Line 027 Alco FA and the s-2 EXCEPT for the coupler: You WILL need the RDC coupler assembly, shown as one of the three RDC parts on the above link. If you call Brasseur's on the phone, I've found them in the past to be most helpful... ask for their most knowledgeable person on K-Line parts.
If you end up needing a motor, it's the same Mabuchi motor used in the Alco FA and the S-2.
By the way, just for your info, YOU CANNOT use the motor truck assembly from the MP-15. The parts all look very similar, but the axles on the MP-15 are just a hair further apart than on the Alco FA, RDC and the S-2. And the motor gears are also different. Nor can you simply swap out the outer plastic truck frame from the Alco, RDC or S-2 on to the MP-15 truck frame.
Yes, you could swap out the truck from one of your dummy RDC's. But will need the gear set (used in the Alco FA and S-2, provided Brassuer's still has them). And you need a wheel puller as both wheels on the dummy truck need to be removed to get the gears in place. A lot of work if you've never done it. Plus as seen in your photo, K-Line attached the coupler for the RDC with a large bottom button rivet. If you bought a truck for the Alco/S-2, I don't know how you would easily go about getting that RDC coupler on to that Alco/S-2 truck as I've never done it. But I'm pretty creative, so I'm sure there is a way somehow.
As far as traction tires, K-Line put them all over the place: On the same axle set as shown in your photo, diagonally with on a geared wheel, and then the other side above on the non-geared wheel, and both on the same side on the geared wheels - which is the best arrangement in my experience and also the way Lionel does it on similar locos. You could remove the traction tire on the non-geared wheel and save it to put on the other side as needed. I adhere my traction tires with double sided carpet tape, so there's no slippage, When they're worn out though, they ARE worn out.
Final thought for the moment: You might want to consider looking about for a 3-unit RDC breakup, just buying the powered unit, and switching shells if your replacement is a different road. If you end up needing a motored truck and a circuit board, by the time you add that up, buying another unit and keeping the one you have for spare parts might be the way to go. Yeah, I know, prices on the bay are in many cases, totally and utterly ridiculous with no basis on market reality. Those folks are either wishing upon a star, or smokin' something real strong. BUT in the past, prices on the K-Line RDC's were more reasonable than the Alco FA's or the S-2's.
One more thought in case you're a schemer like me: You CANNOT use parts from the RMT 'Buddy" RDC. Yes, it is very similar to the K-Line predecessor, but also very different. The motor on the RMT Budd car is a higher voltage one than the K-Line low voltage motor. The coupler arm is die-cast and very similar to what Williams used. (RMT had previously been produced at the Sanda Kan facility, the same place where K-Line had been produced). Plus the shell on the RMT version has alterations to accommodate the directional LED lighting and roof strobe light. BUT you could buy a RMT Budd car if you find one with a similar road and use that with your K-Line dummy RDC's.
