Recently purchased a 450SL. It has square headlamps rather then the dual round. Pictures on the web show both. First, why the difference in the same year model and second I need a high beam. I pulled the complete light out, but it appears the bulb is replaceable. However, I can't figure out how to get it out of the complete unit. And, finally, can i upgrade to brighter HID or LED lights using the old housing? Much thanks!