Chattering from front end over 30MPH

[kingmetal]

Truck started to develop a clicking / chattering over 30MPH, sounds like it's coming from the front end near the transmission tunnel hard to tell with high frequency stuff). ALMOST sounds like it's coming out of the vents (obviously I've turned the AC/Vents off). Truck needs to be driven for about 15 mins before it becomes audible, then it gets fairly audible (about 30 mins of driving) and doesn't seem to get louder. Cycles faster with higher speed, NOT RPM. Does not change pitch with steering. Not super loud, not super scary, but annoying. When you start to slow down, the "tempo" of the noise slows as well. I've seen this issue described on F150 forums, but no resolution.

Had some other folks ride along and listen to make sure I'm not crazy. Had Ford drive it (they claim they drove it for more than 15 mins on two occasions) and they couldn't hear anything. I needed them to do the airbag recall on this truck and was just frustrated / short on time so I just dropped it off without making a service adviser ride along with me, which was stupid of me.

Recently had the hubs apart (ball joins replaced) and they inspected OK as did the axle shafts.

Reason I'm putting this in the 4WD forum is I have an inkling it might be the front driveshaft. It's an 04 so the front driveshaft is spinning in 2WD if I understand the system correctly (hubs are always engaged). I'm open to any and all suggestions, but I was wondering a couple of things:

1. The front hubs are always engaged, so does the transfer-case disconnect the drive-line from the transmission in 2WD or does the front diff have a disconnect in it? This is more just out of curiosity.

2. If I pull the front driveline to isolate the problem, is it alright to drive relatively long distances without the front driveline in the truck? Anything I should know before I do this, such as tricks to keep t-case fluid / diff fluid from getting contaminated.

Edit for potentially relevant details:

Virtually stock 2004 Ranger XLT 4WD Auto 4.0 V6 145,000 on the clock.

 

[hondaxr650]

I have seen the c/v joint in the front driveshaft go bad and cause a clattering, rattle sound. The shaft unbolts from the flange on the t/case, so you don't need to worry about fluid loss or contamination. You can drive it as far as you want without the front driveshaft without causing any problems at all. The front driveshaft is engaged by the t/case, no differential disconnect.

 

[pjtoledo]

sounds like a dry ball in the front driveshaft CV joint. when it gets worse it can shake like hell.