[jocko]

did the same thing. It actually comes with the wiring that goes all the way to the fuse box. So, two ways to go about it:

1) snip the wires behind the existing dome light so you can completely remove it - also cut the wires to the new dome lamp short about 5-7"-ish - then splice the old to the new.

2) snip the old dome light off, but HANG onto the wires, and then wrap them firmly around the end of the new ones on the new dome lamp - and use them to fish the new dome lamp's wires thru the drivers side sail panel. Takes a little time, but certainly doable. The absolute key is a tight connection between old and new. I wrapped them together, then doubled them over themselves, then taped the whole thing really tightly (about 5" worth of overlap and 5" worth of tape. Once you've fished it out (it kinda comes out to the driver's side of the cab fuel tank (if you've got one) and then snakes under the sill plate up to the fuse box. Find the old wires and it will all make sense.

Biggest "be careful" with either approach is to not drop the old wires back into the cab before they're either spliced into the new dome lamp (#1) or firml;y attached to the END of the new wires so you can fish em thru. Should be orange and white if I remember right. They can plug into the fuse panel right where the old one did.

I did option #2.

(EDIT - Sorry, don't mean to confuse, I said "wires" - but I'm not sure if it was a one or two wires - whatever came with the kit is the correct #)
(EDIT #1! It really helps to also push the wires from the dome lamp end while you are pulling them from the "old wire" end below the sail panel.)