So the difference with master cylinders is the bore.
A "71" drum brake master has a 1" bore. A "74" dics brake master has a 1" bore.
I see no difference?
Reason I ask is it's time to get a remaned booster/master for the 68 which has 77 disc. I have a 71 booster/master to use as a core and don't see why I would go to the later year when they have the same bore..
Anyone want to put in there ??
the difference is the check valve thing in the drum master. it isnt in the disc master. with discs you dont want it in there it wont let the brakes work properly. so you want to get the disc master to match you disc brakes.
gotch ya. thanks Craig
Can I use the disc master with the "smaller" 71 booster?? or should I just go with the bigger booster??
Are the brackets the same??
the firewall mounting brackets for our trucks will fit either booster. the size of the booster is dependant upon the single or dual diaphrams it has in it. i do not know which is better to have.
the smaller one must be a the dual diaprham then. because it is wider. as long as your not using a 460 in there either will fit. if you put a 460 in there you have to either use the smaller booster or flip the bracket to help move the booster upwards so the valve cover to booster cleance is enough it doent interfaer with each other.
Hey Craig, if you get a chance check out the boosters listed in NPD- http://npd.dirxion.com/WebProject.asp?B ... flx&from=2
They list a 68-71 drum booster W/master as # f2005-2
Then they list a 72 with disc as the same f-2005-2. this was another reason I was thinking I could use the 71 like I have.
i would stay away from them if they say they are the same master. i looked in my paper catalog and they also had a non adjustable rod type for a 72 F-2005-3. i only know what is on this site. i am not a trained mechanic in any way except on my personal cars and trucks. if i read something i can remember it. that is all that makes me a poster here really. is my memory. i have seen where guys have came on here and had brake pressure troubles because of the things in the drum brake master. i did read that they could be removed though. i cant confirm this i have never done it.
yes that is basically whati have read on here it is the residual valves that are different per drum /drum and disc/drum masters. so npd doesnt seem to know what is what when listign thier parts just as do some of the other places.
i didnt even look at that avatar. it is a small world after all. i was over at ford fe today and noticed alot of names from other sites i go to. i rarely go to ford fe because i am not in the race/ hot engine build scene.
??
this was another reason I was thinking I could use the 71 like I have. 
