I purchased Hella H4 lights from this place, they also have the relay harness and a lot of good info on the different bulbs.

http://www.rallylights.com/hella/wiring_harnesses.asp

If you go with the H4 lights you will have to open the back of the headlamp holder on the truck.
I drilled semi circle of 1/4 holes and used wire cutters and a half round file to open it up.

I had these about 20 years ago a had forgot how good they work.