Hi, i rebuilt my car last year and its been running brilliantly, i'm rebuilding it again now during this quarantine. For the wheels what i've done is bought new 12mm hex wheels as well as new 12 mm hex's. I also have new drive shafts, hub carriers, spindles, motor and many more new items for the car. The Bycmo is very flexible when it comes to the parts, but not that flexible with the gearing. I have bought many new set of gears and non of them seem to fit. Any help would be great as i don't want to keep buying plastic spur and pinion gears.