Sure looks like the HP lens (at least from the back).  It has
the slight curvature to the sides and the mounting looks the
same. A guy named Clint was asking me about bulbs, and he had
a split/dual wind with 320 turns on 5 poles (times two) and 
he figured he needed about 1500 RPM to get full bright on a 
55W bulb.  In contrast, the 320 turns over all 10 poles pulls
a 55W and a tail+brake light (25W or so) to full bright at
even a low idle.  I've never been a fan of the fragmented power
you get from a split winding.  In Dirt Rider's 24h they take
a system with split windings runnning 1/2 AC, 1/2 DC and 
convert it to a single winding with all DC so that the 
power isn't fragmented.  I think it was a WR. Not sure.
P.gortamaker