OBS 7.3's have 90 CC injectors, no intercooler, and a smaller high pressure oil pump. The early 99's were a step up and the late 99's to 03's better yet, I think 120 or 130 cc injectors, intercooler, 17* high pressure oil pump and better air flow into and out of the engine.
You can really wake up an obs 7.3 with aftermarket (bigger) injectors, slightly bigger high pressure oil pump and some custom tunes to match the engine mods. Do not buy out of the box programmer for the 7.3 engine!!
Tranny may need mods after engine mods, but if driven responsibly will last a while before needing strengthening.
Hope that helps.
