[tincan1966]

1) Is there 12V at the brake light switch orange wire?
2) With the brake pedal pushed is the 12V on the white wire?
3) With the pedal pushed, is there 12V on the white wire on both sides of the turn signal plug on the steering column?

If the answer was YES to all three, then with the pedal pushed is there 12V at both the yellow and green wires on the turn signal switch connector? (make sure the turn signal lever is not in the left or right turn position)

If the answer is no, then you have a failed turn signal switch-either the contacts are worn or it is burnt internally. Since you stated you have turn signals on the rear, I am going to bet on the white wire not making contact in the switch, unless you answered NO to either 1,2, or 3. if that's the case repair as necessary and resume testing in that order.

This is about a 10 minute test that will tell you exactly where you are losing the voltage.
There is no sense in running all around the truck checking bulbs. The bulbs are only 2 element and there's only 3 wires that run everything to the rear(unless you have backup lights.)
Stop and turn signals share wires, which originates from the T/S switch. If the turn signals work then that was your test for the harness from the T/S switch to the lights.

Always test from the source to the bulbs, it'll save a ton of wasted time. If you do not have power it doesn't matter what the bulbs are like.