Originally Posted by RCGaryK
here's what you can add to your BK1 to bring it to CR specs:
XXXCR FRONT SHOCK TOWER - LOSA1104
FRONT ARM, VLA, EA3: XXXCR - LOSA1112
XXXCR STEERING BELLCRANKS, RACK - LOSA1621
REAR SHOCK TOWER,EA3: XXXCR - LOSA2100
REAR HUBS, VLA: XXXCR - LOSA2129
REAR SUSPENSION ARMS, VLA,EA3:XXXCR - LOSA2132
Those are the main components. I would also consider swapping out the graphite chassis and front/rear suspension mounts with EA3 ones as well.
To add, the most important part of the "cr" conversion is the pivot block (not on the list above. The arms won't work without it, the pivot is wider, the arms are shorter. This pivot and rear arms are the foundation of the cr. Everything else is warmed over from other versions of the car.