Difference between the D130 and the D130A, OLD STYLE?

[Eric M.]

I have one of each. D130 had an aluminum dust cap (I'm not sure if it was original). Both 16 ohm. both need re-cones.
What was the difference between the 2 models?

D130, 16 ohm (Single) (Old Style) Ser. # 5104

D130A, 16 ohm (Single) (Old Style) Ser. # 10944

Thanks,

Eric