I am looking into changing the pickups on my bass.
Will any set work or do I need a certain .
Im talking about size, not type

I have a Greg Bennett Fairlane FN-1 w/ JJ pickups.
Yes any J pickups should fit.
Im not sure what the bass costed when you bought it but often you are better of getting an entire new bass then a new set of pickups.

But in answer of your question yes J style pickups a world standard so any brand should fit but it never hurts to ask in a store or to take your bass with you.
To Be is to Do -Socrates-
To Do is to Be -Sartre-
Do be do be do -Sinatra
check out the Basslines pick-ups from Seymour Duncan.
"If I was any cooler I'd be froze">>>Me

Epiphone Les Paul Custom,
Yamaha: FG-405
Yamaha: FX370C TBS
Squier Vintage Modified Jazz & Fretless Jazz
Vox AD30VT
Traynor DynaBass 200T
Hohner Button Accordian
Digitech RP350
i know my bass is cheap (it's my first) and i'm looking into getting a five string. but thanks
look into basslines
they are awesome pickups
My Gear

Squier VM p-bass(i chosed it over a fender!!!) with quarter pounder and gotoh 201!!
fender MIM P bass
epiphone SG 400