They do make a gasket, I know, I bought one for my truck when I got water in my diff and had to drain it. It was like 4 bucks and its a cork gasket. But I'm not saying you can't use rtv that's what was on my truck when I took the cover down.

 

ok cool glad thats cleared up i would much rather buy a gasket than Fing with trying to get a perfect seal with rtv

 

Sh** i gotta do mine too, 90k is probally bad if its never been done.
i'm just not excited bout doing two of them. i can't just do one.

 

I'm just about to do mine tomorrow, it's got high mileage, and this truck hasn't been driven lightly and I'm sure it's never been changed I can't wait to feel the difference. I'm definately taking the cover right off, it may take a little longer if it all and it's worth it to know that you have a fresh seal on it. It would suck to change the fluid then have the seal go around your cover.

 

Oh, and I'm just using RTV. I've done it a bunch of times to trucks and I've never had a problem.