Well Ive never done any fabricating but I can cut and weld! So no pics yet because im gathering the metal but if someone could help me with dimensions and give me some ideas on how to attach it. That would be awesome!

 

http://www.jcroffroad.com/product/XJMISC/XJRK-MT.html

I would try rain gutter mounts like these. I just used U-Bolts on the factory roof rack bars to secure mine but its not the best way. They tend to knock themselves loose sometime.

 

I have seen these. They are very nice.
Just make sure the rack is big enough to go to (toward) the edge of the rain gutter,and you may want to get 6 clip-ons if the rack is really long.

 

Hmm never thought of using those. And i made it 45 by 65.

 

50" wide fits the XJ nicely. The length depends on what your intended use.
Anything narrower than 50" is harder to access, and looks like a tiny little hat imo.
My rack is 50"x81". I use it to carry bikes, kayaks, canoes, lumber, and camping gear. The nice thing about this size is a sheet of plywood fits and is easily secured. The length does hang over the back but only 15".

As for the mounting, I made my own gutter mounts because I wanted the rack to sit as low as possible. I'm using 4 per side or 8 total. I would use any less on this size rack.

Good luck and be sure to post up some pictures.

 

50" wide will land the edges of the rack at the same width of the stock roof rails you have/had.

6.5ft long will take up the entire roof. Imo 5ft looks best. I have built about 250 roof racks since high school....

Gutter mounts are the way to go.

 

did mine using some heavy duty van ladder racks in the gutter, with a bunch of u bolts. holds really nice.

 

+2 for these. They are what I used and have held up great for 5 years now.

 

im building one now, I went 48 wide because most material comes 48" wide, it worked pretty good...