for an HID light source. Period. They are available for the MDX, as HID headlamps became an option a couple years ago. So, either head to your dealer or hit
www.car-part.com (searchable used parts) and pick up the assemblies. length for proper focusing" is not a "get out of jail free" card. It doesn`t change the fact that the optics of a headlamp are designed for ONE light source. A halogen *OR* an arc discharge source. It doesn`t matter that the wrong light source is in the right place -- it`s still wrong. The MDX halogen headlamps produce extremely high levels of glare even with just the normal halogen bulbs -- you propose to triple it. (nominal). Modifications from this give much less light. Example: Philips and Osram both sell a 6000K burner. Its output is nearly 1000 lumens less than that of their 4100K burner.
There are many unsafe, illegal and noncompliant products on the market, mainly consisting of an HID ballast and bulb for "retrofitting" into a halogen headlamp. Halogen headlamps and HID headlamps require very different optics to produce a safe and effective -- not to mention legal