After much research I still don't know the first year of AC drives on Yale reach trucks. There is a dealer on eBay who has two 2004 trucks supposedly with AC drives. But the more I look into it that seems highly unlikely in 2004. I have a Crown reach truck brochure from 2006 and AC was not standard on Crown then.

The other reason is when a Yale truck did have AC drives they plastered a large decal on the truck proclaiming such and I have yet to see a single photo of a 2004 or 2005 Yale with such a decal (on original paint machines of course...but one would think even on a repaint the dealer would want to replace that sticker in particular...and yet no one has)

So, for me, the mystery continues....