Ok so how long can a bad U joint last in a front axle? I say these just because we are still waiting on the new one and the one on there now is pretty bad.

 

It needs to be replaced as soon as possible, if it grenades then it could mess up your shaft, seal and could even damage splines in a severe case. If at all possible it should be replaced before it gets any worse

 

you can buy yourself a little time if you keep it in 2wd.
once you put it in 4wd, there will be too much pressure on the bad joint and like said above, you risk blowing it and taking out your shaft and seals.

 

^^^...what they said.

 

I'm not sure how much they are on your side of the pond, but you can get one for $9.99 at any autozone/NAPA/advanced auto ... Even a cheap replacment while you wait for a good one to get there is worth the piece of mind knowing you're not going to grenade it while heading to work or out parking with the girlfriend.