So I have an 04 Endeavor LS AWD that has been pretty bullet-proof for the last 3 years, except for a propeller shaft replacement right after we bought it. Anyway, within the last month, it has developed a vibration between 60 and about 80 mph, and only when you accelerate. Take your foot off the gas, vibration goes away. I can feel it through the steering wheel and in the floor, and the harder you accelerate, the more violent the vibration. I have taken it to 2 shops, the first telling me there was nothing "visibly" wrong underneath, and that it was possibly a "torque converter shudder" and the second telling me I likely had bad front axle shaft(s). When I asked how to be sure it was the axle shafts, I was told the only way to tell was to replace them and see. So I checked, and Endeavor axle shafts are OMFG expensive, so that's not a gamble I want to take right now. Any ideas? For the record, I have 97,000 miles on it, the tires are a year old and the entire suspension is original to the vehicle.

most likely its the inner axle on the passenger side. the boot is made of a "high temp" rubber as opposed to all the other boots on the carl due to the fact that it runs right over the exhaust. which is good, but for one thing..

they're porous. the grease physically leaks THROUGH them. so , if you have a look at the inner joint, ill bet its covered in a film of grease. and it also probably has none left in it.

the axle will probably need replacing. you can get just a new inner joint from mitsu, but there should be lots of aftermarket suppliers and rebuilders available for less... although who knows the quality.
or get a used one.

Thanks for the advice. I'll check it out tonight after work.

How expensive of a repair is swapping out an axel?