So, as suggested, I tried it. My Revell is undoubtedly at the bottom of several boxes–I’ll save that one for later.
But I did find my Varney switcher body.
Definitely NOT a slip fit. But I think it can be worked out:
The “fuel” tank on the Athearn chassis is .012 wider than the available space between the air tanks on the Varney. Some carefully done filing can remove the metal from the chassis.
You will also have to file some more off the frame near the"fuel" tank–you’ll see it when you try to do that slip fitting.
You are also going to have to file a bunch of the deck under the cab to allow for the Athearn gear tower.
Mounting couplers and attaching the body to the chassis is NOT straightforward. Right now, just looking at the parts, I don’t have a decent solution.
There’s not a lot of clearance front-to-back for the shell to fit over the gear towers. I think it would fit, though. One thing you’d probably want to do is remove Athearn’s light bulb mounting bracket. You might have to also do a “clever trick” to have the cab rear clear the gear tower.
My Varney body casting is bare. Which means there’s no cab. So I can’t tell you much about clearances there. I was planning on using a Cannon cab when/if Cannon produces more.
As a matter of interest, the Varney body casting (without cab or end steps) weighs 3 3/8 ounces. The Athearn body weighs 5/8 ounce without the cab.
I will also note that the Varney cast is REALL VERY NICE. The doors, for instance, are flush, rather than raised, as on the Athearn.
So, since the Varney is NOT a slip fit, I am still suspicious about the Revell being so.