Atlas/Roco Shells, Modern Atlas frame?

I was looking though the atlas site, because I need some Dash 8-40B handrails (ironically for non atlas versions of this loco) and I thought I'd just look around, because their parts department is, lets face it, awesome for the kitbasher.

Anyway, There are new GP40 and SD35 frames out there.

I have a pair of old Roco GP40s and an SD35 sitting around and as anyone whose had these knows, the frames, specifically the fuel tanks are just really really bad.
So I'm wondering, if I buy new frames and fuel tanks will the motor and trucks just drop in?
I'm sure I can make the frame work. It's mainly the trucks that I'm worried about. Will the Roco trucks work?

And before anyone suggests it, I've put a lot of work into these engines in details and cleaning them up. I don't want to just replace them If $12+ shipping will fix the worst of the visual problems. I'll take it.

 

Look at both instruction sheets and or take apart the old roco one and compair. You might need alittle cutting and kitbashing and or just use the new trucks with the frame and old motor

 

It's hard to tell.

The more modern versions appear to be pretty much exact copies of the Athearn truck. At least in terms of structure.
The old Austrian Roco trucks use a similar mounting method, but the worm gear tower is different, so it's not entirely clear if the pin is in the same location.


I suppose an alternative would be to simply find someone or buy the tools needed to cut the fuel tank down myself and then buy just the fuel tank. That seems like more work though.