What's involved in replacing standard rack and pinion with H>D> rack
 

I have a 2006 H3 and it needs a new rack and pinion. What parts would I need to change to install a heavy duty one? I'd appreciate any help you couls give me. Thank you.

No HD rack available.
Best to upgrade the mounts to the OD kit below and install your new rack. Haven't had an issue in years since the install and I run 37s and wheel it regularly.
https://www.outfitterdesign.com/stee...ement-kit.html

OK, My local parts store has 2 options for a rack and pinion for my 2006 H3. one has 14mm tie rods and the other has 16mm tie rods. I want to replace the 14mm rack with the 16mm rack.

The rack is the same the tie rods and ends are different. Not really a regular and HD thing.
GM changed them in late 07 (for the 08 model) if I recall correctly.
06-07 14mm stock, but can be upgraded to the 16mm if you do both inner & outer on both sides.
08-10 16mm stock.

Hope this helps

The change to 16MM was in 2007, early mid year. My 2007 came from the factory with 16MM tie rods. The 14MMs were supposedly discontinued after that and I would think it would be quite a hunt to find ACDelco 14MMs in 2019 on purpose. Would have to be left over NOS. Not to say you could not find cheap aftermarket Asian brand 14MMs.

Yeah, mine is a mid year 2007 and I have the 16mm tie rods.
I installed the Outfitter kit 6 years ago and haven't had any steering rack problems using 35's and hard wheeling.

I live in Mexico so things can get a bit unusual down here. I found both the 14 and the 16 at Auto Zone. It turns out the 16 was a bit cheaper. The roads down here are pretty rough, lots of cobble stone. The whole front end was pretty hammered so I went ahead and replaced all the moving parts and installed the 16mm. Thanks for all the information it was very helpful.