cross reference for fuel injection pump and injectors cat428D BMT02630

hi. machine cat backhoe 428D BMT02630 my backhoe has no power/less for a ride, my friend told me that is probably because fuel injecton pump is leaking fuel, is it pomp delphi dp200 ? he also told me the is should check fuel injectors. when im buying new pump what letters/numbers must be the same ? how about injectors are they also delphi ? what is part number ? im thinkin to also repalce them, is the injector holder and nozzle one complete element , should i replace all 3elements because replacing not complete makes no sense ? im asking for part number becasue cat part prices are probably 2x more...