need part numbers for replacement rubber brake lines

[l79m20]

I have a 1966 GMC 4000 which runs great but does'nt stop well. The culprit is the rubber lines that attach to the steelbrake lines coming out of the master cylinder. they are roughly 6 inches long and both have female ends at each end. I am interested in the original numbers if someone would have those so that I made order new replacements. These are not to be confused with the rubber lines to the wheels. Thanks in advance

[VictoriaHardware]

Do you mean the ones that attach the body lines to the frame? You can see them in the LH wheel well?

[l79m20]

these lines are connected to the two lines that exit the master cylinder's twofeed ports, one steel line snakes down toward hydrovac and six inch rubber hose connected to it and the other end to the hydrovac. The other steel line snakes toward the rear of the engine (v6) with the rubber line attacthed to steel line and the other end to something and as this line is not damaged I have not followed it to its end. Does that help.

[VictoriaHardware]

Picture(s) would help the most but still may not get the answer you want. Does not sound the same as my '65 Chevrolet C80. Anyway, I could never find any info on similar brake lines so I had to get all the details- length, end fitting thread type & size, male/female. Still had a tough time finding anywhere to make them up. Tried numerous internet and local hydraulic hose fabicators. Finally got an antique auto restoration shop to make one. The other I made from steel tubing & fittings. There is enough "play" in the whole system so the hard line does the same job as the rubber did.

That second line you haven't traced yet may be the hydraulic clutch slave cylinder, mounted on the lower right side of the belhousing.