I have slight vibration at highway speed. It seems like it is coming from the rear driveshaft once I shift into overdrive. I crawled under jeep today and grabbed the driveshaft, and it has some play in the splines. My question could this be the cause for the vibration?

 

Not sure, but I don't think so. Have you checked your PSI? Did you check your tires for any bubbles or missed nicks/slashes? Any mud stuck inside the rim? Are your tires balanced properly? Could be at highway speeds, the problem is amplified...

There are many possibilities, need a little more clarification...

 

do you have a 2-door or 4-door? is your jeep lifted? if so, do you have an aftermarket drive shaft installed? if so, did you install adjustable rear upper control arms so that you can set your pinion? if so, have you checked to make sure that it is set properly? you'll need to provide a lot more background before any of us can provide any real assistance.

 

Sorry for the short description. It's 07 rubi 4 door with 97,000 miles. Has a small BB, not sure the size, came on the jeep when I bought it. I don't believe it's the tires. Like I said it only does it on flat road when ur in overdrive. If u accelerate it goes away or if u let off. The reason I believe it's the splines in the driveshaft, had a cherokee that felt the same way when the splines got play in them. I was wondering if JK had the same issue.

 

Sounds something like a bearing.... when you have load on it (aka throttle or breaking) it stops.