Mark can you recommend a dye to use with the pressure test?
No dye for pressure test just what it says your testing to confirm integrity of cooling system. Use the dye to narrow down what fluid your dealing with, dye in transmission fluid or in engine oil etc.
Also, how does the chemical test for head gasket work? Is it like one of these:
http://www.amazon.com/UVIEW-560000-Combustion-Leak-Tester/dp/B000NPDL76
that's it exactly, you can buy and use or pay as much or more for Johnny grumpy pants at the shop. Maybe less if you toss a six pack on the counter of the corner station, dealers not so much.
I have not seen any smoke in the exhaust, no loss of power (other than when the a/c compressor kicks on). Good small leak hopefully or just leaking to outside. Test compression in each cylinder to confirm which one or where. I usually don't because ill figure it out when I've torn the engine down enough.
Coolant level does definitely drop, I haven't been keeping a close enough eye on it to tell you the rate of the leak though.
Yikes
Figure that out
Checking the oil, do you mean by taking out the drain plug on the oil pan?
Not always use the dipstick
My dipstick is worthless, It always reads empty even after a fresh oil change. I guess it isn't long enough.
Fix this if you plan on keeping the truck
The oil on the bell housing is engine oil. It isn't gear oil, and it isn't P/S fluid, i know that for sure.
Ok
I doubt it is brake fluid from clutch master or slave because the fluid level is constant in the reservoir. It is dark brown, just like used motor oil. I am suspecting a leaking oil pan gasket at this point but i can't really see it well enough to know for sure.
What kind of tests can identify if the oil leak is the rear main seal or a leaking oil pan seal?
The best tool to use is the Mark 1 Eyeball. Made popular by conundrums like "where did I put my beer" and "that's not my wife, is it?" The Mark 1 has seen constant and severe duty in every climate on earth and has never failed to note the obvious. Proper use however demands exposing the suspect areas for assessment. Wiping and degreasing is the first step. Get all the old **** off so you can better track the nasty. Jack her up, and using all safety devices like chocks, straps, ebrakes, ex-wife behind the wheel fire up the ol beauty and every so often climb under and take a gander. Especially with the ex-wife behind the wheel.
Sometimes ill line the area with scrap cardboard to spot leaks faster. Find it, back track it and fix it.
Disclaimer: you should really make sure the truck isn't going anywhere when you get under it. I do it with the engine running, you should make sure it's off.