I just got new rotors for my 67 Mustang and need to know do just the bearings get installed into the rotor? The bearings I got are the correct number as6 but they do not fit over the spindle. This is the inner bearing  

Doowop63 - There are likely several people here that will have the exact answer you are looking for. I had a 68 and I found that having the correct spindle and rotor are critical. Did you check the new rotors to the old ones? Are the inside diameters the same? If not then they may be for a different year or just incorrect for your application. If you have the correct mics you should measure the spindle diameters and the inside diameters of the bearings to see if the spindles are larger than the bearings. It sounds like the bearings are the correct size for your new rotors but, are the new rotors correct for the spindles?  

Here's the strange part the inner bearing will not slide over the spindle completely. the passenger side went on fine. I have checked the NAPA site and all of the bearings call for the same inside diameter 1.25? is there a larger spindle that may have been placed on my car at some point? I read 70 spindles are the same geometrically but are slightly thicker?  

Where did the bearings come from in the new rotors? All new rotors (with hubs) that I've ever installed have no bearings or races. You transfer the old stuff to the new or you buy new bearings and races.  
Did you swap the pass side the left side and see what happens (the rotors & hubs don't care what side they're on)?

I have no knowledge on the 70 spindle dimensions but the parts store should be able to answer that question for you too.  

check to make sure when you pulled the old rotors you didnt leave behind a spacer or something..sounds like it. then recheck the new bearings. maybe the place you went to get the bearings gave you the wrong one or it was the wrong one in the box. it happens. i feel something was left behind when doing the swap...check and triple check.  

Old rotors had inner bearing and grease seal intact when I sent them to be cut. New rotors have race installed. I have tried two different sets of bearings. One from NAPA and one from Advance auto. All of the references for these bearings show ID as 1.25" I believe I am correct that the rotors with grease seal and bearings should "bottom out" when installing on the spindle. These bearings dont make it over the tapered part of the spindle  

Do you have access to a dial caliper?  I would check to see if the diameter of the left spindle and the right spindle are the same. I would also check for a burr on the offending spindle. I would be willing to bet eitheer you have a burr or you have a different spindle on one side(granda, lincoln, something) but be careful with trying to "fudge" this or "make it work" some how.  Remember this is what holds your wheels on, and after years of playing with cars I have come to the conclusion having all your cars wheels attached to the car is important. Good luck and let us know what you find. Tom  

You're right the inner bearing shoulder should abut the spidle grease seal boss. However, the same question i asked you before still applies. Does the other rotor fit on the side that the new one doesn't?  

Thank you all for your help. I found after searching on several different sites, a gentleman who confirmed several things. 1 the spindle on my mustang is the correct spindle. There was a small area on the underside of the spindle, where the previous bearing had spun, leaving a barely detectable "burr". After several minutes with emory cloth and varying grits of paper, a shiny smooth surface allowed the bearing to seat correctly. I would like to note for those thinking their cars have the wrong spindle when decoding the Ford stamping, the correct spindle does decode to a 66 Fairlane spindle. Once again thanks to all who helped me out.