Although I haven't pulled injectors on this particular motor, I've pulled injectors on several other diesel motors and they are typically held in by the compression of a bracket with two bolts that keep the injector pushed into the hole and it required a bit of a pry with a roller head pry bar to pop them out.
Thanks, I have them out. Last month the engine began blowing white smoke and this was on the list of getting to the cause. It took alot of pulling. Looked like maybe they hadn't been checked or cleaned in many years, one totally bad. Hoping after cleaning and new tips she will purr ...... and no smoke.