I attempted this a few weeks ago, different connector on the airtex pump than the plug on the pump itself. Plus I couldnt get the old pump out, ended up buying a full assembly (ouch my wallet!).

If anyone wants to make an attempt I'll sell you the pump I bought NIB $45 shipped with extra hose, high pressure clamps, and a new filter sock! (blah blah go post in classifieds I know sue me)

 

Lol isnt that crap how some of these trucks have one kind of plus and some have another style plug thats the same thing as the blower motor wiring harnesses they are not all the same.

 

Tell us these things..
Flashing Alarm LED.

1) When you first enter the truck.
2) When you go to ON
3) When you try to start the first time.
4) When you go to KEY OFF
5) When you go to key on the 2nd time.
6) When you start the 2nd time..

I am wondering if you are immobilized the first time and then somehow you get free and can start the 2nd time?

This is a guess. But, nothing else makes sense.