Dave, you are a pessimist. At least you are rarely disappointed... <img src="/forums/images/graemlins/smile.gif" alt="" />
Solution #1: Don't look under the truck.
Solution #2: Take the truck to the car wash and spray the motor all over with engine cleaner, then with the car wash engine cleaner, then with the HP soap, and then rinse. I'd put a plastic bag over the coil and distributor and keep direct spray off them, not a real area of interest except at the dist. base and the drive extension on the head under it. Let the engine dry (you can drive it home) and then do a dusting in the suspect areas with one of those little squeeze bottles of baby powder. You want a even dusting, not wads and gobs. Concentrate on these areas:
rear cam plugs and the seam on each side
valve cover gasket
front cam orings and the dist. drive extension
front main seal
rear main seal (there's a sheet metal cover that goes over the part of the tranny bellhousing that hangs below the rear of the engine you can remove to get a look at the bottom of the seal area - buncha 10mm bolts hold it on)
Now blow the loose powder away. If you have a leak, it should show as a trail of powder stuck to the oil.
An altenative that costs more is UV dye in the oil, then hunt the leak with a UV light and the funky glasses.
The rear main seal is the most expensive, and thankfully one of the least likely. Most likely is valve cover gaskets - they get hard with time. With the valve covers off, you can remove and reseal the rear cam plugs easily. You have to reseal the upper and lower halves of the rear cam bearing - there is no gasket there, just metal to metal, and it needs a smear of rtv on the faces, as well as in the "square" corner the valve cover gasket turns as it goes over the hump of the rear cam bearing. The front main seal seems to go before the rear, probably because of the belt side loads. When was your timing belt done? If it's time for that, the front main seal is part of the job, along with a new water pump and tensioner and crank bolt. While doing this, it's relatively easy to reseal the front of the cams as well.
There are writeups on all the above procedures, and all are doable by the average home mechanic with the proper usual tools. The only oddball part you might need are cam sprocket locking tools and a holder for the harmonic balancer or flywheel so you can torque the crank bolt.
