Sometimes you’ll find Marx train cars with Lionel couplers on them. The first thought is someone changed the trucks, but closer inspection reveals those are Marx trucks under the car. How’d they do it? Here’s the secret of converting Marx couplers to Lionel.

Both Lionel and Marx made adapters for this purpose in the 1950s. Marx’s adapter was intentional; Lionel’s adapter just happened to fit both its cars and Marx.

The Lionel adapter for converting Marx couplers

You can convert Marx couplers to Lionel by replacing the Marx coupler with a Lionel 480-25 assembly as shown.

The more generally useful adapter is Lionel part number 480-25. Lionel made this part for upgrading its low-end Scout cars from the late 1940s, which also had incompatible couplers. This part also happens to fit Marx trucks perfectly.

To use it, flip the Marx car over and pry one of the tabs holding the coupler in place slightly with a slotted screwdriver. Lift out the Marx coupler and the spring that operates it. Keep the coupler and spring in your spare parts drawer.

Then place the Lionel 480-25 conversion assembly over the axles. The Lionel part has four tabs that clamp down over the axles to hold it in place, two per axle. A pair of pliers works well for clamping the tabs down. They don’t have to be super tight. Just bend them down enough to keep the truck from bouncing around.

These parts cost around $7, so converting a whole fleet of Marx cars can get expensive. I recommend you change one coupler on a common Marx car, such as an 8-wheel 347100 gondola. Then you can change types in the middle of your consist using that car.

This modification is completely reversible. To revert back to stock, simply un-bend the fingers around the axles, remove the Lionel 480-25, and pop the Marx tilt coupler back in place. The spring can be difficult to replace, but here’s a trick to make it much easier.

This modification is also helpful for running Sakai and Marx together, since the Sakai coupler is compatible with Lionel.

The Marx coupler adapter for Lionel

Marx produced a coupler adapter that converted its tab and slot coupler to a Lionel dummy knuckle coupler. This part is in shorter supply than the Lionel coupler, since Marx only shipped it with its large tin Santa Fe diesel locomotive. The parts you’ll find today are probably reproductions. This part will fit the tab and slot couplers on any Marx car, and can be forced onto a tilt-type coupler on later Marx 8-wheel plastic cars. But the Lionel part makes for a cleaner-looking conversion, and is in more plentiful supply.

One more modern alternative

There’s one more modern alternative for converting Marx couplers to Lionel. Scientific Toys makes cheap plastic train sets, sold under the Eztec brand. Their O gauge sets tend to show up in discount stores around November and can also turn up in secondhand stores. It happens that the Eztec coupler fits the Lionel coupler very well. You can remove the Eztec coupler, then drill out the rivet in the Marx car, and re-fasten the coupler, with the Eztec truck beneath, with a half-inch 6-32 screw and 6-32 stop nut. If you don’t have any 6-32 stop nuts, you can use a regular nut and secure it with some Loctite.

This conversion is cheap but of course less reversible. These sets retail for around $15 and usually yield about four couplers. A secondhand set is even more economical, of course.

Be careful when you’re looking at Eztec sets, as Eztec sells a lot more G gauge trains than O gauge. The G gauge train won’t help you in this case. Eztec sold freight train sets in the past, but in recent years has sold a two-car passenger set called the North Pole Express. The O gauge sets aren’t labeled as such, so you do have to eyeball them.

After harvesting the couplers, the Eztec passenger cars make a good conversion project. They look good with 4-wheel Lionel or Marx trucks installed and running behind an O27 engine.