Bought an 06 with 145k on it. Original owner, older gentleman, took great care of it. Ticks under a load only. Purse like a kitten at idle. No codes or performance issues. Sounds like it's coming from the lower right side of the engine. Exhaust leak?

 

Hmmmm... I'm looking at an 04 with the 5.4 81,000 miles, but now you are all scaring me...
How much should I worry about this motor/truck?

 

It can get very confusing to use anything other than pass or drivers side .
Ticking can be caused by exhaust leak /cracked exhaust . Injector noise . Lash 's /rollers in head are frequent problem . Phasor pins .
Keep her clean use MC filter /good drain back valve in it . No extended oil changes . I use 5w30 syn change before 5k and I use some marvel mystery oil . Combustion carbon is the problem not the slipperiness of it .
VCT cam control is a hydraulic system using dirty engine oil with screens and small passages . Thick additives/oil etc will only mask and prevent oil from getting thru .
Plastic tensioners and guides have a high failure rate , plastic jams oil pump screens. On a rebuild use old style metal ratcheting tensioners with no seal to blow out . Plastic tensioners only apply pressure when oil pressure up so every start is a problem . Chain whip breaks plastic guides .