RE: Serial Number cut off?
I don't believe they ever beefed up the arms and you can tell if you got the updated cvd/axle asemblies by looking at the axle cup where the cross pin lives.If it has 4 holes (2 unfilled) then they are the updated axles/cvd's.If you'll lok at the picture the updated axle is above an original and you can just make out the extra holes
Hope this helps