02 RAM, no power when truck is off

2002 Dodge Ram, 4.7. THe radio does not work at all, interior lights won't work, power locks, neither head lights, everything is dead unless I turn the truck on, I checked all the fuses and seems that they are good, I did replac the 20 amp fuse in slot 51 as with the other (2) 20 amp fuses for the radio and interior illumination (21 and 22 I think) and still nothing. Any other suggestions....what could it be?