I dont see where the problem is, looks like the bearing sits on the same spot on the new pinion, so I would think it would work. You do have two bearings on the pinion right? What kind of driveshaft do you have? the set screw it came with should thread right in if its a stock driveshaft.
The set screw is larger in the driveshafts I have. And yes I had two bearings in it. I'll toy with it some more. I know it's hard to understand without being hands on. And my lack of RC knowledge. So many small seemingly unimportant but very important parts......


