Where could I get a new one ? Its off a 1999 4.0 liter engine looks like a 5/ 16 tread about 8 inch long

 

Seems like a pretty easy bolt to replace. I would hit the auto parts stores like pepboys first. they have a good collection of bolts and nuts for cars. Then I would check the home stores and see if they have one to match. Otherwise you are hitting the JY or dealer for an OEM. How did that bolt break?

 

I would hit a JY first.. easiest and still the correct bolt...
P.S. Loosen the idler pulley bolt first, then the tension bolt will move freely...

 

I was trying to loosen it to change out the alternator but it was really rusted. I took out the 3/8 bolt first and sprayed wd40 let it sit for hours repeated this a few times and the bolt snapped anyway. What is JY ??

 

Thanks to all that replied, I just ordered the part from a jeep dealer.

 

JY is junk yard. Better get familiar with it.

 

Thanks, My past has been mostly new cars so I almost forgot that term!