So, only the rears? Then one would have mismatched colored shocks. not very fashionable.
Here's the snippet from the wiki for other fitments depending on what tower you're using. Fronts are the same.
Q: What Kashima shock bodies do I need for the B6/B6D?
A: For the front, you will need #ASC91576 12x23mm Buggy V2 Front Shock Body
For the rear, you will need #ASC91577 12x27.5mm Truck V2 Front Shock Body
For the rear, you can also buy #91666 B6 Rear Shock Tower (Long)
and #ASC91578 Buggy V2 Rear Shock Body
So basically, B5M fronts and Truck fronts if you want to be same as kit form. Or, 31mm rears if you want to use the long tower.