6 litre and 4L80e finally fitted to my '89. Went off without a hitch in three hours with just myself on the job.
With the mods i made to the gearbox it is a perfect fit with ample clearance with no body mods to the trans tunnel and original 6 litre rear mount is a direct bolt up to existing mount holes.
Control is via EZ TCU fitted in left hand footwell.
Even the original trans shift set up works fine with only change an earlier shift cable a little shorter overall

 

Keep us posted with how it goes, very interested.
Greg

 

I connected the same TCI. My first sensations: It's like KAMIKAZE shift gears. It is necessary longly to adjust

 

Would have been really interesting to get some acceleration numbers before and after the swap. The only (rough) comparison I've ever seen are on Keisler's and John's Cars websites.

 

Awesome!! I am just a few weeks behind you. I had to swap over all my accessories off my original 5.3 to my xj40. 6.0 and I had my driveshaft for the 5.3 shortened 3.0 inches. I also have a 6.0 xjs rear trans mount. Hopefully mine will be going in the car this weekend. All should be pretty straighforward except for the wiring. That is the only thing that concerns me. I plan on using the original trans and motor ecu's. I purchased a used 6.0 xjs motor/trans ecu wiring harnesss as all the connections are in the correct places. I will have to splice some of the original ignition and fuel injection harness to make it all work. After the motor/trans are in I will focus on the wiring. Good luck and keep me posted on your results.

 

I like how you modified the trans cooler lines much cheaper than what I did. I ended up have some -08 an fittings welded to the cooler side and had new trans hoses made at my local hydraulics company.

What are you doing about the engine oil cooler. Are you running a passive system from the 5.3 or the full flow system from the 6.0?

 

I hope your swap goes as well as mine has so far.
Engine oil cooler will be unchanged as my '89 had full flow system anyway. I crimped olives onto the trans cooler lines prior to fitting rubber hose to prevent any chance of them simply slipping off the pipes.
One thing I did find with the swap related to clearance is the need to lay back the flange where the firewall joins the trans tunnel just where the dip stick/filler tube runs. I did that with the trans in the car but it would be much easier if you did it before.