Big-dawg

Hi all I am looking for help with my d/boys p90 I am in the process of upgrading it I have a new gearbox on order to take a lipo, a new barrel installed, but bits of my hop up unit have broken and I am wondering where I can get a new one and what is the best type to go for. I have been told by my brother that all are universal but I am not one for taking him at his word. Any help is great guys. Cheers