You could try "Supermaxx" in Ebay ansd see if any are there. Also UE might have them. The Hyper 7 I believe has 8 spyders. You could look on Ofna website too.
http://www.rcmart.com/catalog/rc-hyp...4aac1b49468c84
this might be one. otherwise it may only be the center diff. i am not that familiar with ofna products.