What size hardline for disc brakes up front?

[Harrison.]

I've done a little digging and have read that drum brake trucks have 1/4" line all around and disc brake trucks have 3/16" line up front and 1/4" out back. My truck is a 70 model that someone has put discs on up front but front lines go through a tee fitting from the MC to 3/16" line and then use adapters on the hoses to go from 7/16-24 flare fitting (for 1/4" tube) to a 3/8-24 (for 3/16" tube). I'm about to re-build my brake lines and trying to figure out which I should be using?

[lolife99]

I always use 3/16" hard line for disc brakes.

[davepl]

My thinking is for the front circuit each side has it's own line, so smaller 3/16" is OK. The rear shares a line, so gets larger 1/4" until the tee.

[67 chevelle]

Ive done several disc retrofits , and what the factory had for drums , worked fine for discs

[lolife99]

And I've run 3/16" hardline to the rear for drum brakes without issue.

[Harrison.]

Thanks guys! I ended up making them out of 3/16" because it's what I had on hand and using the adapters for the hoses, I was just confused why there were adapters at all in there.