Master cylinder 1-ton 1966

[geasson]

Well, it is running. Rough but it is running. It has no brakes and fluid is leaking out the back of the master cylinder and leaking on the inside. I suspect a new master cylinder is needed or at least a rebuild kit. My issue is that I have the rectangular master cylinder and according to the catalogs, a 1966 should have a round master cylinder. Did the PO change to an older master cylinder or did the 1-tons continue using the rectangular master cylinder. Which one should I buy???

[Simonsays]

I think as long as the bore size is the same it shouldn't matter. I have a 3/4 ton 1966 and mine takes the round one. You can take your apart and measure the bore size of the piston. I believe I saw it's either 1 inch or 1 1/8 inch.

[Ed Snyder]

Well, it is running. Rough but it is running. It has no brakes and fluid is leaking out the back of the master cylinder and leaking on the inside. I suspect a new master cylinder is needed or at least a rebuild kit. My issue is that I have the rectangular master cylinder and according to the catalogs, a 1966 should have a round master cylinder. Did the PO change to an older master cylinder or did the 1-tons continue using the rectangular master cylinder. Which one should I buy???

The one on my 1965 one ton is round, but it has a screw-on lid.

[geasson]

It looks to me like there is little consistency in master cylinders. I guess I will need to get it removed and measure the bore and them find one. THanks for all the input.