Going to be doing a Head gasket rebuild, What else should I replace while im in there?
This is what I have so far. Head gasket kit, coilpack ,waterpump, timing chain kit, oil pump gears, machinists straight edge, feeler gauges (check for warping) what else am I forgetting?

I'm not pulling motor, doing in vehicle

 

good to have those o rings for connecting hard coolant lines, too.
they really should include those with the kit, but they don't

 

also, some flex conduit to replace all the cracked junk you will find. and a quantity of cleaning supplies

 

Unfortunately top end rebuilds are becoming a 'national pastime' for LR and D2 owners in the US. What's the biggest cause of HG's failing and how often/miles do they fail?

 

Average Around 100000 miles +\- 20k
They just deteriorate, unless you overheat....

 

Things I did on mine during the HG job recently (aside from what you've already mentioned)


radiator
all hoses
180 degree thermostat
crank sensor (was easier to get to so I figured why not)
upper intake gasket
TB heater kit/TB gasket
crank seal
front cover gasket
oil pan gasket
pickup tube o-ring
oil filter adapter o-ring
oil separator
exhaust manifold outlet studs/nuts and outlet gaskets
head bolts (I'm sure you already know to replace these)
condenser fan motor


plus quite a few other things not really related to the job at hand, so I won't get into those.

 

timing chain kit, oil pump gears,
in order to do this you need to drop the oil pan so make sure you get the appropriate gaskets and a new front seal

 

- Thread chasers to clean bolts and threads in block (you can get a loaner kit form Auto Zone)
- Thread sealant for bolts that go into the water jacket
- Loctite (certain bolts need it, Oil pump bolts)
- 180 deg Thermostat
- check/replace idler pulleys/bearings

Make sure that you have a 8mm or 5/16" 12 pt socket for the valve cover bolts

 

1/4 drive works best if you are painting your valve covers.

Also a few cans of brake cleaner for keeping everything sterile.

 

tons of parts heavy duty parts cleaner, engine assembly lube, 9mm hex socket for the SAI adapters that go into the heads.....beer and naps for when it gets frustrating, which it can and will....just go one step at a time, document everything, torque everything to spec and stay organized