How to tell the difference in 76-77 BB and 66-75 BB axle

[Blue71]

I am looking at a set of axles in my garage trying to figure out what year they came from. The bearing and backing plate is on them. NO HOUSING! Is there a way that I can tell if they came from an old 77 rear end I had a few month ago, or a 66-75 parts truck. I know the bearing is a little over 3" so its a big bearing, but how can I tell if they are from a '77 and not an earlier Big Bearing housing? Do the lengths of the axles differ for 76-77? I know the drivers side and pass side differ, but do they differ by years?

Thanks,

Blue71

 

[Viperwolf1]

'66-'75 lengths are different than '76-'77 lengths due to the difference in brake width.

 

[Blue71]

Any idea on the length of a set of early BB's compared to 76-77 BB?

Thanks,
Blue71

 

[Viperwolf1]

I got this list from completeoffroad.com a long time ago but the brake sizes don't look right to me.

66-75 (SMALL BRG) (28 SPLINE) 1 3/4" BRAKE R.H..29.62"
66-75 (SMALL BRG) (28 SPLINE) 1 3/4" BRAKE L.H..27.25"

66-75 (LARGE BRG) (28 SPLINE) 1 3/4" BRAKE R.H..29.31"
66-75 (LARGE BRG) (28 SPLINE) 1 3/4" BRAKE L.H..26.94"

74-75 (LARGE BRG) (28 SPLINE) 2 1/2" BRAKE R.H..29.75"
74-75 (LARGE BRG) (28 SPLINE) 2 1/2" BRAKE L.H..27.25"

76-77 (LARGE BRG) (28 SPLINE) 2 1/4" BRAKE R.H..29.68"
76-77 (LARGE BRG) (28 SPLINE) 2 1/4" BRAKE L.H..27.25"

 

[Blue71]

Much appreciated Viperwolf. Thanks a bunch..I am getting my tape measure out I think your right on the brake sizes above not being correct. I think for 66-75 SB it should be the 10 x 2 1/2" from what i've read WH cataloge.

Andy
Blue71

 

[cs_88]

How about this.

 

[Blue71]

How about this.

Whoa..thats nice. Thanks a bunch. Appreciate the help and diagram. This might be good over in the Tech Section.

Thanks again,
Blue71