The high current fuses are located in the Power Distribution Box on the left fender-well under the hood. There are 2 types of fuses (mini, like in the passenger compartment, and maxi) The mini fuses are on the left in a double column numbered from the bottom up, and left to right. Fuse 1-11 left, fuse 2-12 right.

1 20A Trailer running lamp and backup lamp relay
2 10A Airbag diagnostic monitor
3 15A All unlock relay,Driver unlock relay,door lock switches
4 15A Rear air suspension
5 20A Horn relay
6 15A Radio,Amp,CD changer
7 15A Main light switch,Park lamp relay
8 30A Main light switch,headlamp relay,Multifunction switch
9 15A DRL,Fog lamp relay
10 25A Auxiliary Power socket (next to cigar lighter)
11 XX Not Used
12 XX Not Used

The Maxi fuses are numbered starting above the mini fuses going up and then left to right.

13 XX Not used
14 60A/20A 4 wheel ABS (60) Module switch RABS only (20)
15 50A Rear air suspension compressor
16 40A Trailer tow battery, Engine fuse module(fuse 2 of 2)
17 30A Shift on the fly relay,Transfer case shift relay
18 30A Power seat control switch
19 20A Fuel pump relay
20 50A Ignition switch
21 50A Ignition switch
22 50A Junction box fuse/relay panel battery feed
23 40A Blower relay
24 30A PCM power relay, Engine fuse module (fuse 1 of 2)
25 30A Junction box fuse/relay panel ACC delay relay
26 XX Not Used
27 XX Not Used
28 30A Trailer Electronic Brake Controller
29 XX Not Used

Relays on the right numbered bottom up.

3 Wipers Hi/Lo
4 Wipers Run/Park
5 Washer Pump
6 Fuel Pump Relay
7 Horn relay
8 EEC Power Relay

That should cover most of the fuses and relays in your truck.