There are several ways to go about this, I used this kit http://www.jbconversions.com/products/dana300/plate.php and their 4:1 kit. I didn't turn mine up flat, just halfway up from stock. "Worth it" just depends on your use, less lift and more clearance. You'll have to modify your skid plate or build a new one to take advantage of this.
__________________ '81 Scrambler w/ FI 360 AMC, 33x12.50 BFG M/T's, 5" of lift, ARB'd Dana 44's F & R, Dana 300 clocked & twin sticked w/4:1, Warn XD9000i, etc...
2002 Grand Cherokee Limited, 2008 Overland Grand Cherokee, a 1976 CJ-7 in pieces and 3 more off-brand 4x4s............... John N
JB's is a thicker ring and replaces the front input plate of your t-case so it needs to extend your shaft to make up for the gap (hence the new input shaft), JB's is somewhere in the 7/8"-1" thick range. Most all other clocking rings are steel and are 3/8" thick. Don't let the thicknesses worry you, I have never seen or heard of a standard clocking ring fail. For some reason it looks like JB is over engineering their stuff to make it absolutely 100% bullet proof, but you do have to shell out the cash for it.
I used JB kit and it was great except it doesn't come with new shims for the new output shaft bearing. Keep in mind by clocking the tcase you change your driveshaft angles and may result in needing a cv joint. Also the spacer will change length of the shafts by close to one inch.
82cj7 / soa wrangler springs / amc 360 / t18a granny / d300 twin stick / 37" pitbull rockers radials / h1's / 3/4ton d44 with high steering / 14 bolt ff / clocking ring