I am thinking about rebuilding a blue box Athearn GP-35 and I have a A-Line GP-35 chassis with a nice can motor. I ordered a blue box Athearn GP-35 Soo Line #729 at an online auction thinking I’d use the chassis and parts as spares for my other blue box locos. I won a GP-35 Soo Line #729 engine but when I received the loco it had the old motor w/steel flywheels and metal truck sideframes. Does anyone know when Athearn first produced the GP-35 Soo Line #729? I thought it was after they rolled out their “improved” blue box with brass flywheels and plastic truck sideframes. I talked with Athearn, the current personnel really don’t know when the loco was produced.
The BB GP-35s have been around since the late '60s-early '70s and are one the old wide-bodied models (not to be confused with the newer RTR using the updated ex-Railpower bodies) and as such started with the round motors with the sintered iron flywheels. As far as the SOO body, I don’t know when that was first produced, maybe someone else can answer that. The owner could easily have switched bodies. And as you’re going to put it on the A-line/Proto Power West chassis, does it really matter?