Can you elaborate more on works fine in reverse but essentially not in drive? What is your description of fine??

As in you can go as fast as the jeep will possibly go while in Rev. But when in drive only it bogs down?

Any check engine light or stored codes?

When engaging reverse and backing up, the engine, etc. are operating as is considered normal. I suspect I could back up as fast and as far as I want, however I could not go far, because when engaging the drive function for forward, the Jeep starts shaking and making sounds like the engine is about to fall out.
If I go as far as I can in reverse, I will not be able to get the Jeep back in the garage in "drive" mode, due to the terrible shaking and the idle bogging down considerably. to almost shutting down.
Check engine light appeared when starting but quickly disappeared. I do not have the testing equipment required to obtain and codes. The Air Bag Light remains on.
Thanks for your help
JEA

Really wild guess.

Some wiring/electrical connection is getting torqued one way when you are in D that it isn't in reverse.
Might try ( with the thing running, in N, parking brake on, ) moving wires around to see if can duplicate funky running.
Also. How are the engine mounts?

Thanks for the idea. I will give that a try.
Any reason to believe that the 90amp alternator is inadequate for an XJ with A/C?

No.

Did you disconnect the auto gearbox connectors ?

They control the forward solenoids

Its possible you did not plug it back in, or damaged it

reverse needs no solenoid

I doubt it would be anything to do with the alt, but I would check every fuse, especially the one that controls voltage to the TCM (trans computer)

Did you disconnect the battery ?...I have been guilty of not doing that as recently as yesterday

Trace all your steps you preformed. Because changing the alt should not create the symptoms you described.