Red line is around 4500RPM or 5000RPM cann't remember off the top of my head.
XJ is the model desigination, like TJ, YJ or CJ.
Grand Cherokees are ZJ or WJ depending on the year.
Old full size jeeps(cherokees/wagoneers) were SJ.
Commanches(truck version of a XJ) were MJ.
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'89 XJ 4" lift, Warn Combo mount and 9.5ti!
31s, 4.10s and rear lockright!
That's enough(for now!)