It all has to do with the trans it is mated to. When mated to the 42RE in the GC, not so great. To the AW4 and the AX15... good stuff.
It seems with the emissions garbage (like 3 cats) on the late 2000's and up came sub standard parts. ive seen a lot of posts about cracked pistons and flexplates, more so with newer XJs.
My 96 runs like a champ, with old age issues here and there, but still runs strong with 270K.
Im the guy who makes new gauges, check out our gallery at Teamadw.com