tick could be valves...CV axles can be done by a novice mechanic for much less...if the timing belt hasnt been done or water pump do both, water pump is behind the belt...not a bad price for both, though im not familiar with the other part mentioned...

exhaust leak will sound like a tick, especially if its around the exhaust manifold, where does it leak? injectors also tick quietly, dont get too anal about noises, a healthy 3.4L will make some noise (rotted steering shaft boot will allow the injector noise into cab)

is it worth it? how many miles on the truck? if less than 200k i wouldnt hesitate if your going to keep it.