Thats pretty simple actually.
This one is different in outlook from your 64 shaft. So, are you a purist or anorak or do you just want it te work as designed ?
You could have yours rebalanced and the UJs replaced. Try that first. If you are happy. Fine. If not replace by this one.
Beware, you hasve the old style, thin shaft with two UJs both with grease nipples , and the 8mm bolts. Later style has no grease nipples and 9 mm bolts.
Check out with Jim at AH before ordering.
JIM IS A GOOD MAN...$ 80 USD parts, labor $165 ( WITH RE BALANCE) and there is still a problem ??? As I mentioned I will keep all parts as we are custodians of these wonderful early cars ... that said am leaning toward the new AH drive shaft...but still would like to know others experience... Thanks