Wow, and I thought I was a Tamiya junkie for trying to run a TA03 in VTA !!
That statement means that because of the mechanical limitations of the chassis and the motor mount....you simply won't be able to install the necessary gears to achieve the right gear ratio that a brushless motor requires. This is typical on many older cars. They simply weren't designed for brushless motors or lipo batteries.
It would be terrible to try and adapt the TA02 for this. You're better off with another chassis. If you like Tamiya, the TA05 or TB03 would be perfect.
Oh, FDR stands for Final Drive Ratio. Thats the gear ratio we most concern ourselves with because to high or to low and you can burn up a motor or do damage to the esc and possibly even the car.