Same spider for both if compact. Only thing that is different are Rings
For example: this crank below (sorry not GXP) is the same as the CX1 crank
https://www.ebay.com/itm/Sram-Force-22-Carbon-Crank-Set-170mm-110BCD-BB30-Speed-Road-Bike/232627415058?hash=item3629aca812:g:-DYAAOSwIBJaV5J5
For example: this crank below (sorry not GXP) is the same as the CX1 crank
https://www.ebay.com/itm/Sram-Force-22-Carbon-Crank-Set-170mm-110BCD-BB30-Speed-Road-Bike/232627415058?hash=item3629aca812:g:-DYAAOSwIBJaV5J5