Please help me out you guys....

I really need your help you guys..... I don't know if you guys remember about my post a few days earlier talking about the nickel plated yoke (Clunkerado finally gone), and I don't understand something... the noise is still there...I think.... The nickel plated yoke is supposed to go in the transfer case... and the yoke is located directly underneath the seat where my butt is... but I don't understand... Now there is, well maybe there was before...but I am not sure... but the same dawm clunking and it is felt underneath the car where the middle of the dash is...(this is NOT the intermediate steering shaft clunk)...I was wondering there is a small shaft about 1 in a half feet long that goes from the, I think it was the front axle to the transfer case.... it looks really rusted...or dark, dark brown... could I maybe have to change this, could this be making the clunking noise under the...? Also, I heard something about the front axle, which people are having a problems with, but I can't remember what it was... does anyone know? Can anyone help my solve this problem and put the clunkerado to rest.... Also, I read that you are supposed to change a "vent" in the front axle, when changing to synthetics..... what is this....could this have something to do with it? Please help.....????????

Is the rusty 1 1/2 foot shaft the front driveshaft? If you have a solid front axle, it could possibly be making the noise. However if the front diff is mouthed on the frame, that is probably not the problem.