So I just recently bought an 01 suburban LS. The guy said it needed new brake lines. Bought new line and loan a tool double flaring kit. The guy I bought it from, he said he reused the factory flare nuts but they don't like going in. What's the correct thread pitch on these? I don't want to potentially damage the abs block because I almost wet my pants when I saw how much even the used ones go for. Was told the nuts are 1/2 x 20 at O'Reilly

Info: 01 suburban LS, abs equipped, NP246 case, JC5, not NW7

 

Hopefully you already solved this but if not, i just went through a whole brake line replacement. I got the prebent lines but I did crossthread the ABS block but got a working used one on ebay for $125.

i did have to reflare a couple lines but the fittings are common ones, my wife stopped by autozone and got the right ones based off the old one.

 

ALWAYS thread in such fittings several turns by hand to avoid cross-threading.