95 ram 2500 w/ cummins, tail lights (but not brake lights) and all dash lights went out. All fuses test ok. Any suggestions? Possibly a relay? Not very mechanically inclined, but learning with this truck @ 320,000 miles and going strong

I would guess a short somewhere if all the fuses are okay.

Being that the 'tail-light' fuse is OK, it is probably an 'open circuit'.

If the front parking lights/roof clearance lights are working, that pretty much checks out the switch and front harness, i.e. everything but the bed wiring. The bed mounted lights have a separate harness that plugs into the forward chassis harness - this would be a good place to start checking.

If the front marker lights are not working either, then it would likely be the headlight switch assembly (the instrument lights also not working tends to point toward the switch). At 10+ years switch contact failure is a good bet.

'94 2500 CTD ... 12 years into a 5 year paint-job.