Well...after 3 days I finally got around to installing my whole PA hookup. Here's the shopping list:
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Cobra 19 Ultra-III CB Radio - $34.95 (Wal-Mart)
RadioShack 50W PowerHorn - $49.99 (RadioShack)
3.5mm Jack (set of 2) - $2.99 (RadioShack)
30 ft 16-gauge speaker cable - $5.99 (RadioShack)
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Start to finish: 1 hr 30 mins.

1.) First I took out my old Maxon MCB-30 CB radio and installed the Cobra 19 Ultra-III. Just my luck that the Cobra fit perfectly in the Maxon's mount.



2.) Rolled the truck up on the ramps we use to change the oil. Properly blocked off the wheels, put it in 1st, parking brake, etc. I went under the front bumper and had an idea where I wanted to mount the speaker. I held it up, marked off the 3 holes and then proceeded to drill out the holes. Hold up the mount, compare, and drill a few holes inward and wha-la!

3.) Went in the garage and found 3 brand-new (again, my luck they were the perfect size because the PowerHorn didn't come with any, -1 RadioShack!) self-tapping screws. I held up the mounting bracket and went around and used a socket wrench and screwed them in nice and tight.



4.) Then put the speaker back on the mounting bracket and positioned it so it is facing the lower grille but not touching that little oil cooler thingy mabobber above it. Fits perfect.

 

5.) Got 1 of the little 3.5mm jacks and used a smaller wire and soldered it on (so it would fit together in the end) then an inch later, soldered on my 16-gauge wire and fed it through the hold (took 20 mins to do this part!) under my seat.

 

6.) Wired up the PowerHorn and ran its wire back thorugh the springs and control arm (I'm worried it might be in the way, but I have it tucked pretty good) and met the two in the middle and soldered together and taped off.



7.) Done! w00t! Looking for something to do, I tie up my driving lights wires and wrap them in black electrical tape to make them blend it. I also fix the loose ground wire that was making them flicker on and off whenever I hit a bump:

 

Here's the vids:

http://www.youtube.com/watch?v=sPKRp45WHj8

http://www.youtube.com/watch?v=nY0gnxRFxCQ

My next project is to hard-wire my CB and fix the left powepoint on my truck (it blew out a few years ago)

Special thanks to:

MmmBuckles, for giving me very useful info (jack size and wire type)
Mike, at RadioShack, for putting up with my annoyance for 2 weeks,
and everyone at f150online.com with a PA that got me motivated!