Rear brake lines/wheel cylinders

[Acregger]

Guys, what am I missing here.

So my I put new brake lines on my 71 k10 rear is 1/4. I took the rear shoes and hardware off to paint the backing plates. I ordered new hardware, shoes and cylinders. I have tried 2 different wheel cylinders and they both are for 3/16 brake line. It just so happens I took everything apart before trash night so my old cylinders are gone. I did take photos so I could put everything back correct. trying to figure out which is wrong cylinders or lines? BTW it was a brake line kit.

Thanks everyone