[MJN]

Originally Posted by 72chevynut

I recently purchased a set of the k20 spicer red dial hubs off the parts board for my parts collection. I took them all apart and cleaned everything. I found a couple of differences between the GM red dial hubs and the next gen blue dial hubs. The red dials don’t have a groove notched in dial for the C-channel style seal and use a thin o-ring instead. I also compared the red dial chrome outer rings to a set of blue dial chrome rings I have and found them different to. The blue dial chrome rings have a deeper notch cut into them than the red dial ones due to the larger c-channel seal used. I believe this would be the design upgrade done between the GM 1970 Red dials and 71 Blue dials. All the other dials I have for the later Model year GM’s and some Ford ones I have, all have the notch for the larger c-channel seal. Hope this helps clear some thoughts up.

Good info- this helps explain the 1st Design and 2nd Design noted in the parts diagram posted above.