I have a 2002 4.8 that came with a 2003 intake.
I also have a 5.3 wiring harness from 2001 or 02.
Next step is figuring out what to do with the fuel
injectors -- swap them out or replace the clips on
the wiring harness? Which is probably cheaper?
Any problems using a 2002 harness/PCM with the
2003 fuel injectors, if I were to go that route?

I'm still confused if LS1 injectors will work or not?
It seems like everyone has a different opinion.

 

the injector clips should all be the same for the years you listed.
ls1 style injectors use different injector clips than the truck ones.

 

All my searches have indicated there's a difference.
Although maybe it's only injectors and not the clips?

If the clips are the same, will a pre-2003 PCM work
okay even if it's using the 2003 fuel injectors?

 

Here's my (2003) injector and (2001) harness clip.
Kind of seems like it should fit, but I wasn't able to
*easily* get them to connect. Maybe they do not
really go together? Does anyone have a close-up
picture of a pre-2003 fuel injector for comparison?

 

I think I see the problem, those injectors look like there Flex fuel. The good news is there about 33lbs/hr, the bad news is they use a different plug

 

That's what I've been trying to confirm!

What I really need to know is... Will LS1 injectors work?
Do I *need* to use pre-2003 (FlexFuel) truck injectors?
Or can I simply get FlexFuel inj clips for my harness and
can I assume a pre-2003 PCM won't care which injectors
they are and work normally? (With the exception of any
tuning needing to be done due to a change in volume...)

I'm just trying to find the cheapest route to fix it.

 

To use LS1 style injectors, you would have to change the pig tails and and space the fuel rail up 5/8 of an inch. Your cheapest way to go would be to find some flex fuel injector clips and spice them on to your harness and then put the 33 lbs/hr in the injector flow rate table of the tune. That way you already have the increased fueling capacity for future mods

The other option is to find a set of non-flex fuel injector (24lbs/hr) and put them on you motor. The year doesn't mater, as the non flex fuel injectors are the same from 2000 to present.