First of all try this stuff on the oil fill tube:
http://www.napaonline.com/NOLPPSE/(S(uk05fum5oif04k55lrdjp4mf))/Detail.aspx?R=BK_7651210_0229695449
It is not silicone but works better in my opinion.
Second I had a problem with oil pressure also. I replaced the sending unit and it was indeed the problem. It looks like this one, i dont remember the exact part number but this one is pretty close and may be the one you need. Only $9 too! I paid about $20 i think. As i said before use a thread sealant rather than teflon tape because the cast piece it screws into is cast and will break if you over tighten the sensor. Here is a link to sensor:
http://www.napaonline.com/NOLPPSE/(...683_0167729581&An=599001+101994+50028+2028036
Someone already mentioned it but i will say again that the leaking rear seals could very well be caused by a clogged axel breather. I had this same exact problem with my orange truck. Just take the rubber hose off and make sure it is cleared out and then make sure the brass fitting is clear as well. We used a drill to open mine up even though this method would result in possible contaminants falling into the axel housing. It solved the problem though with the leaking rear seals. I never noticed them leaking again. It is amazing sometimes how something so small can seem like a big problem especially when a bunch of small things happen at once.
Far as the power window motors I have replaced them as well. It requires taking the interior panel off the door and drilling a hole which is premarked at the factory (dunno why they didnt drill it at the factory). You just unbolt the old motor and bolt in the new one after that.
As far as the RDT that thing doesnt matter as long as the line is clear of clogs. It is just a crackcase vent and can be vented anywhere! You could vent it up over the cab if you wanted too as long as the oil that condenses on the tube can drain back without causing clogs.
I feel for you because i hate working on the truck when it needs something, I prefer adding accessories instead.
I always try to tell myself that some dummy put this thing together so I ought to be able to fix it. Hang in there!