Exhaust manifold gasket?

There's a metal gasket between the cylinder head and the exhaust manifold. It's actually in two pieces but they're held together with a connecting strip that doesn't get sandwiched between anything. If that connecting strip gets rusty and breaks free, it can hang down. If you can twist it to break it off, that part can be thrown away. If any of the sealing parts rust away, you'll have a loud ticking noise. That is especially easy to hear from inside during periods of moderate to heavy acceleration.

Chrysler doesn't use gaskets between the manifold and exhaust pipe. If you have to take that connection apart, you can expect the little tin clips that hold the nuts to break and let the nuts spin when you turn the bolts. Those clips are only meant to hold the nuts during assembly, then their job is done. It's hard to get a wrench on those nuts to hold them, and if you can, they're usually rusted too tight to spin them off with hand tools. It's much easier and faster to use an air-powered cutoff tool to cut through the bolts. The holes in the manifold are not threaded, meaning you can just lift out and discard the top parts of the bolts.

The exhaust manifold has nothing to do with oil leaks. The only thing going through them is exhaust gas. No thread locker is needed on any of these bolts. Using that will just make it that much harder to take them apart next time.

Start by looking for the highest place you see oil. It's going to run down from the source of the leak unless the radiator fan blows it around.

When the source can't be located, there's a couple of things we do. One is to pressure-wash the area first, then add a small bottle of dye to the oil. After running the engine long enough, we search with a black light. The dye will show up as a bright yellow stain that can be followed back to the source.

The second method only works when the leak in at a non-pressurized place in the engine. That can include the valve covers, oil pan, and intake manifold. Oil will splash around those areas and leak out even after the engine is stopped. For those types of leaks, we can use a smoke machine to inject a white, non-toxic smoke at 2 psi, then we watch for where it sneaks out. That usually doesn't work when the leak is in a pressurized passage. Oil leaks from those places only while the engine is running.

When the leak is from a non-pressurized area, it can be worsened by a defective or plugged PCV valve. That can prevent fumes from getting collected and burned, and will allow excessive pressure to build up. That pressure will help push oil through a leak.

You're buzzing off into totally unrelated areas. A compression test can tell you if compression is low, but another test, (cylinder leakage test), is needed to figure out where the compression is being lost. One of the four possibilities is worn piston rings. That can cause excessive oil consumption, but that will not cause leakage outside the engine. The symptom would be blue smoke out the tailpipe.

Same for the spark plugs. There shouldn't be any oil in the cylinders. If a cylinder head gasket is leaking between a cylinder and an oil drain back passage, that too would cause oil to be burned and go out the tail pipe, but it wouldn't be leaking outside.

The camshaft position sensor is inside the distributor. There is a large O-ring right under the base where it sits on the engine block, but leakage there is very uncommon. Oil there is not under pressure. It would have to splash up there, then get pushed out by excessive crankcase pressure before it runs down into the oil pan. More likely a film of oil would settle around the distributor if that O-ring wasn't sealing properly. If enough oil leaked out there to cause a drip, the PCV valve would be the better suspect as it isn't allowing the normal blowby gases to be drawn out and burned. That results in pressure in the crankcase that will push oil and / or air out through a leak.

The oil pressure sending unit sits right beside the distributor. There is pressurized oil there. Just about the only time you might find oil leaking past the threads is right after a new sensor is installed. Oil won't start leaking there years later. It is possible for the sending unit to leak internally. The two clues there are the entire sending unit will be wet, all the way up to the connector, and, if you pull the connector off, you'll find oil down by the sensor's terminals. The connector has a rubber weather seal to keep water out, so if you do find oil in there, it can only come through a leaking sensor.

One of the byproducts of a properly working catalytic converter is water vapor. When the exhaust system is still cold, that water shows up as steam from the tail pipe. There will also be a small drain hole at the rear / bottom of the muffler. You're likely to see water dripping from that hole too. That steam can also be due to heating up the condensed water vapor that was pooled in the exhaust system overnight. That will burn off within a few minutes. As the exhaust system gets hot, you'll see less and less of that steam coming out of the tail pipe.

If that white smoke continues or becomes worse the longer the engine runs, that is a sign of burning antifreeze in the engine. That's caused by a leaking cylinder head gasket. That can happen to any engine, but it isn't real common with the 3.9L. The first clue is the level will drop over time in the coolant reservoir and you'll have to add periodically. There is an additional chemical test that can be performed to identify that. If you don't have to keep adding coolant, consider the smoke out the tail pipe to be normal. Coolant at the tail pipe will also have a sweet smell to it. Hold your hand there to collect some of the vapor. If it's water, it will evaporate cleanly. If it's antifreeze, it will leave a slimy, oily feeling.

Only do that if you've been having to add coolant. This link is to an article that shows how it is done:

https://www.2carpros.com/articles/head-gasket-blown-test

You can usually borrow the tester from an auto parts store that rents or borrows tools. In my city, they make you buy the tool, then you get a full refund when you return it. If you choose to keep a tool, you still return it, then they give or order you a brand new one.

In this case they are likely to make you buy your own bottle of special fluid. That is because it is rendered ineffective if it freezes or if it becomes contaminated with coolant. They don't want to risk giving you bad fluid that was ruined by the previous person, so they made him buy his own bottle too.

When you do this test, keep an eye on the coolant level in the radiator. You may need to drain some out before you start, plus, it is going to expand a lot as the engine warms up. Drain more out as necessary. Air from on top of the radiator is the only thing that must get sucked into the tester.

Leaking valve stem seals used to be rather common years ago, but not so much today. Oil that runs down the stem into a cylinder gets burned so slowly that you'll never see it once the engine is warmed up. It's when the engine is still cold that oil that ran down overnight pools on top of a piston, then goes out the tail pipe and is seen as a dark blue cloud. That gradually clears up in a few minutes. I've had a few engines with that problem. None of them used oil fast enough that I needed to add between oil changes. When I pulled the engines apart, I found the seals to be badly hardened and they had cracked apart. If your seals are badly worn but not cracked, I don't think you're going to lose enough oil to worry about. It's the blue smoke when starting a cold engine that is the only symptom.

If you have an original drain plug, it will have a built-in rubber gasket. Believe it or not, those are almost fully tightened with finger pressure. A very slight tug on the wrench is more than sufficient to make them fully tight. If one has been overtightened, the threads will start to peel. You may see part of a thread hanging from the drain hole when the plug is removed. At that point the plug must be replaced or it likely will work loose or can't be tightened sufficiently. In real bad cases, it is possible to create a crack on the oil pan around the drain hole. For my own vehicles, I've had good luck sealing up things like that with Chrysler's gray RTV gasket sealer. With their black stuff, it stays a little more rubbery, but it absolutely will not bond or seal through the slightest film of oil. Everything has to be washed or sprayed down with Brake Parts Cleaner or something similar, and dried well, then it might work. The gray sealant WILL bond through a light film of oil and it cures a little harder. This is not a way I'd repair a customer's vehicle as it risks leaking again, but I would try that first on my own stuff. The alternative, if there's a crack in the pan, is to replace it.

For the intake manifold, there's two places oil can leak. One is at the front or rear on a V-type engine. The oil isn't under pressure there, so there will only be minor seepage unless the PCV system isn't working. The second place is when there's oil drain back passages running through the intake manifold and the gasket is leaking. That oil typically gets sucked into an intake passage and goes directly into one or two cylinders. That will be a major loss of oil and it WILL make a blue cloud out the tail pipe even when the engine is warmed up. This is usually seen on four-cylinder engines as they do have drain back holes running through the cylinder head. Your 3.9L is a version of the really rough and reliable 318 c.I, with two cylinders lopped off. There's no pressurized oil running through the intake manifold, so that major leak isn't possible. The oil in the drain back holes is under no pressure. The oil in the other passages is at around 45 psi. Those passages are not close to the intake passages in the cylinder heads, so it's very unlikely there would be oil loss there. A lot of gasket would have to corrode away, then the very high pressure in the cylinders would push combustion gases into the oil system long before any oil would flow the other way from the low pressure to the high pressure area. None of these things would cause leaking oil to be seen on the outside of the engine. Anytime pressurized oil gets sucked into the intake manifold, there will be no mosquitos in your neighborhood for miles around! When you remove the spark plugs, those for the cylinders sucking in oil will be coated with black soot. If it's bad enough, that will lead to spark-related misfires.

I found different part numbers for the two applications. They look quite different too. I use the Rock Auto web site when researching which parts interchange.