Checked around here. A 4200 engine is $1400 to $1800. What are things I will need? Gas pedal, wiring harness, computer,transmission. How big of a radiator will I need. What kind of fuel pump will I need. What kind fuel pressures? Thank y'all again!
Gas pedal - yes
Wiring harness - yes - including the body harness from the PCM into the cab upto the gas pedal and the diagnostic port and if you can upto the gage cluster.
Transmission - depends if you want to run the 4L60E
Best to run an in tank EFI pump - a walbro pump for a grand national is good enough.
Fuel pressure 58 PSI for a return less system (04 and up engines)
Some have swapped the return less fuel rail to the 02/03 return style and run an external fuel pressure regulator.
Rad - go look at the size of a stock trailblazer rad.