hello cruiser people. can anyone explain why if I have a 4.3 tbi with 4.3 injectors, I am supposed to use prom chip #16139566 which is for a 5.7 motor, and cal-pak # 16060836, which is also for a 5.7 motor. thought all that was to match closely as possible to my 2f-4.2. like I should get chip from 4.3 4-wheel drive or something similar to mine. but, knowledgeable people have said that and it's pretty confusing to me. doesn't stand to reason for me, but I am just starting this conversion and don't know much, am trying to understand and figure it out so I get it right. do ya'll know if this set-up will be able to "read" and program itself to my motor with so much difference in size? I can't program one myself[don't have a clue] so trying to be careful here. has anyone done this and said- hey, great, that's just what I was looking for and not had to fine tune it? or, [the worse question I could ask- can someone tune this chip for me?] my motor runs good, I can tune conventional stuff, but I can barely use my cell phone. HA! anyway, have 2f, bored .020, headers, 4-speed, with 4-11 gears. the rest is stock. trying to gain fuel economy over performance. get 12mpg with weber 32-36, kind of retired so can't hardly afford to take a road trip. live in Oklahoma, like to see rocky mountains. don't mind paying for a chip that worked as I would have to buy stuff to tune one anyway [lost again]. seems like there would be someone out there that does that but I haven't heard anything yet. also build log furniture. hell, I would build someone a rustic coffee table plus pay them their asking price! [I make nice ones]. HA! someone please get back to me, I am "desperate in Oklahoma". ya'll have a good day and Happy Trails!