Is there a difference in sizes i.e. bearing sizes, hub thickness among the late 60's 911 hubs and the early 70's hubs? I wanna put a 5 bolt conversion on my car but I don't know much about the differences in the different years.

yes there is a difference...

the spindle is the same, bearings are the same size. The only difference is the lock-nut, on the early spindles its small and fine thread, on the later spindles its larger dia and coarse thread...

I dont know the date the change was made..

BTW Im just talking about updating early 911 to late 911 struts. I know nuttin about 914 to early or late 911 swaps..

Thanks TimT, Well I thought when you swap the 4 lug to 5 bolt, your pretty much changing out to a 911 suspension. The reason I asked about the hubs was I saw these and I might want to use them in A TRG coilover setup.

ok if your using RSR struts, you can use early hubs provided you use the later hardware.. but you have to open up the dust cover area a bit to clear the larger locking nuts....

I have a lathe so getting it all to work wasnt a prob for me...

Do you also have to make it deeper to get the lock nut down further?

nope

these are just some things to watch out for when making a salad of different model year parts LOL

Oh I like making salads, especially making parts fit when they don't. hence shoe horning the v8 thats sitting on my garage floor.

Then there is old 911 T hubs. They are used with solid rotors. They are narrower. Hubs for vented rotors are about 15mm wider.