Here are some pictures of an injector installation on a 1999 Cummins 5.9.

The injector nozzles are some Bosch RV275's from Dieseldawg's injector sale.
Most of the tear down process to get to the injectors is pretty straight forward.
My write up is mainly just to show some pictures and details I encountered.
Remove the four bolts on the intake and the clamp at the intake pipe make sure to cover the openings.A plastic cup works good on the pipe end and a rag or tape over the intake plenum/manifold.
Remove the plastic cover over the throttle control.
Remove the three bolts holding the throttle mount to the block.
Take loose the injector lines from the VP 44 injection pump and the cylinder head.
There are some 10mm bolts that hold the lines to the intake. Don't remove the 8mm bolts that hold the blue spacers in place.
The lines should come off in two sets.
Remove the valve cover.
Remove the Exhaust rocker arm bolts, keep the rocker arm matched with its valve spreader fork and number them 1 through 6 on a piece of cardboard.



Remove the outboard bolt that holds the injector hold down clamp.




Remove the fuel transfer tube from the side of the head by using a special tool from Snap-on or a small #1 flat tip screwdriver to pop it out the only resistance should be from the O ring.





Remove the injector by installing an intake bolt into the top of the injector, thread in a few threads and use a heal bar or small pry bar to pull up lifting the injector from its hole.





I removed the old stock injectors and dissembled and cleaned the injector bodies.

The lower portion of the injector unscrews from the main body with about 35 foot Lbs of Break away torque.

When unscrewed it will allow you to remove the spring and shim washers from the bore of the main injector body.The parts inside are small use a baking pan or tray so you don't drop and loose the small parts.
The copper seal is usually stuck to the end of the injector nozzle ( make sure they all came out with the injector and not still in the cylinder head).
Remove the copper washers and the old nozzle should slide out of the retainer with a slight tap, carbon build up around the old nozzle makes it a little difficult sometimes.

Installing the new nozzle into the injector body is just the reverse making sure its "operating room clean".The shim washers and spring should be kept with the same body they came out of.

Here are the injectors with the new nozzles after they were pop tested by Turbo Diesel in Atlanta. The cost for Pop testing varies mine cost about 20 dollars a piece that included new copper seals and body O rings.






This is the Part # of the fuel transfer tube o rings.



I hope this helps someone out.

Thoroughbred Diesel did a nice Video on you tube about this subject, here is a link.