Balance spring retainer

On Easton vinyl windows they use coil balance shoe 15-177. At the top of the sash there are 2 plastic pieces that interlock. The bottom piece has a post that goes inside the coil spring. The top piece interlocks to with the bottom piece to give it added strength to support the spring.

I've found the coil balance shoe in your catalog, but haven't been able to find the 2 plastic pieces that hold the spring. I am going to need 3 sets of the plastic pieces and 2 coil balance shoes.