Here's what I did to put LED's into my D M-L. The LED fixture is about $12 at West, you need to grind off the ends about 1/16" to get it to fit inside the Davis Fresnel lens cover. Leading the LED wires through the Davis bulb holder will hold the LED's in place. Snip the power wires away from the circuit board, attach them to the LED, and that's about it.
The photos are in the CPYOA Gallery. The second pic shows where the LED's sit in relation to the Fresnel lens prisms when the unit is assembled.
How do you like that fancy duct tapin'? ;)
(http://www.com-pacowners.com/4images/data/media/8/img_1460.jpg)
(http://www.com-pacowners.com/4images/data/media/8/img_1466_sm.jpg)