Electraglide Ref. I vs. Ref. II?

Any Electraglide Ref I/II owners out there? Can you tell me how I can tell them apart physically? I've just purchased a pair of the Mk IIs, but I suspect one of them is a Mk I. The female end of the Mk II is "U" shaped, and the male seems to be a different plug than the Mk I.
the ref I is bi-sexual. the ref II is asexual. sure hope this helps!
Look both the same. Minimal sonic difference. Electraglide changed plugs frequently on all versions so this is not a deciding factor whether you have Mk one or two.
If I were you, I'd send them both in and for a trade-up to the ElectraGlide 2000 anyway.
Jaykapur, you are correct! I am in the process of sending them in to EG to trade up to the Reference 2000.