Front D30 Question

97XJ, 2" budget boost, new 31x10.5's, SYE and tom woods shaft on rear, tom woods shaft on front, all (all 8) U-joints replaced about 6 months (15,000 miles) ago. NP242, AW4, 4.0L engine. D30 in the front, stock gears. Crappy gas mileage (18 max).

Over the weekend I used 4L to crawl up a washed out road, moderate incline for FL. Somewhere in the front drive line was a loud popping noise, speed dependent. Almost sounded like an axle U-joint.

In 2H no noise. In 4H part time on dirt, noise when I accelerate, in 4H full time on pavement also noise when accelerating. Haven't tried at speed, too loud/don't want to launch anything.

I looked at the suspect U-joint today, no rust, so a couple of questions:

1. what is the life expectance of an axle U-joint?
2. If it is an axle U-joint and I continue driving it (in 2WD) will it last a couple more weeks?
3. If it is an axle U-joint and it grenades while in 2WD, will it take the knuckle with it?

Thanks,

Mark

I would kill for 18 MPG. To me that is great gas mileage.

1. On 31's with very mild wheeling I gotta think the life expectancy of a ujoint is 30k-50k miles minimum. Edit: with good ujoints.
2. Maybe, maybe not.
3. It probably won't take the knucle,but it may take the ears of the axle shaft.

The 18 mpg is on the highway doing about 80 with cruise control on. I changed the speedo gear when I put the tires on it, it's close but I'm probably getting a little better than that in reality.

I listened to the noise again at lunch today - I think it's in the front driveshaft. I'll pull it tomorrow night, put the stock DS back in and see if the noise is there or gone. I'm starting to suspect the DS because the sound doesn't change when turning. We'll see.

Thanks,

Mark