Ann/Nancy Wilson - Blue Christmas

Can someone who knows a lot about Heart and/or who has a good ear please clear up some confusion for me?

I absolutely love this version of "Blue Christmas", but there is widespread confusion as to who is singing and even whether both sisters appear on the recording. Based on what some of the more "authoritative" sites (All Music Guide, Billboard and Rhapsody) say, my limited knowledge of Heart and solo recordings by both sisters, I'm assuming Ann is on vocals here and Nancy is on guitar. However, Amazon only credits Nancy and Nancy's MySpace page credits her first "featuring Ann Wilson"...

So, with that in mind, enjoy this ridiculously country, "bluesy" version of "Blue Christmas"

I've been a huge fan of the Wilson sisters (and Heart) since the early 80's. But I have to confess to never having heard this song before at all.
I would guess (and this is just a guess) that this is only Ann on vocals and probably not Nancy on guitar (it certainly lacks Nancy's signature guitar sound). It sounds like a group of Nashville session musicians with Ann's vocals to me (definitely a country version....ala Patsy Cline).

Thanks for the info. I figured it was Ann singing since she apparently did most of the singing in Heart, and a solo song I found from Nancy didn't sound anything like that, but I wasn't entirely sure.