So I have a Fender Mexican J bass and I am looking to upgrade the pups. I am looking for passive pups because unless i make a hole somewhere in my bass there is no room for a battery. Also I do play out and already have an active bass so i guess im looking to expand my arsenal with my hopefully soon to be upgraded passive fender. Most pup sets i find aren't the same size. My bass has the two 3.6 inch length, all the pup sets i always find have a 3.75 and 3.6 size. Does a passive pup set even exist in the same size or do i have to buy two seperate ones??