Iveco Zeta 109-14 brake cylinder (corrected)

Hello, a lot of time without going through here, I have a problem with one of the brake master cylinders, specifically that of the rear axle, these cylinders go along with their corresponding lung, said cylinder drip me, I am trying to look for spare parts, I get cylinders with different caliber, there is also no reference in the old cylinder, I have thought about disassembling the cylinder and measuring the internal gauge, but I would Mount it since I have to work with the truck and the spare takes about 10 days to arrive. I said before my truck is an Iveco Zeta (109-14)

I already solve it, disassemble the cylinder and the medium with the caliber, pedi the corresponding and functioning.