Well back again with this drivetrain noise. The noise is a rattling rumble when you let off the throttle and give it a little gas. So if you hold it at a constant speed it is constantly making the noise. So far I have replaced the transmission, transfer-case(locked up), all u-joints, and roto-flex. I noticed the rear pinion seal has started to leak. I pulled the rear driveshaft and rear axles. When you spin the pinion it feels nice and smooth with no side play. Also back lash feels good. The noise sounded like it was rear but I am starting to think the frt may be the issue. The frt seems to have lots of slop when you twist the driveshaft back and forth. The noise seems to be getting worse but not very fast. I was hoping it just broke so I knew what the culprit was. The rear diff feels good, is it possible or common for this to make noise? The pinion seal is leaking, do I finish pulling it out and tear it down? I fell no rough spots when I spin it. Also fluid is clean with no metal.

 

are you sure its a drivetrain noise? is it a "thump-thump" rattle or metallic?

 

I had a similar noise under those conditions. It turned out to be the u-joint, but you said you changed them. I ignored mine until the front shaft exploded into the tranny and cracked the case.

 

No it's drivetrain noise. I am real familiar with the noise. Just not too familiar with the land rovers. Sounds like excessive backlash. Since the rear diff feels good I will put it back together tomorrow. I am going to pull the front driveshaft and drive it. Right now I am leaning towards front diff, front driveshaft, or transfer case. The transfer case I got is used with a ton of miles. I have another one. I want to see what the front diff feels like. I get no clunk when I put it in gear. When I coast the noise goes away. It is only under constant speed. As soon as you load it by hitting the gas noise is gone.

The more I think about it. If it were coming from the rear the root flex joint would absorb most of the noise. This truck is just frustrating.