This company sells a header for a G200Z in an Impulse, maybe you could contact them and see if they can do something that will fit a Trooper. Or maybe the header they make can be modified by you to fit. They ain't cheap!!

http://www.isuzuperformance.com/bills/engexhhead.html

I also saw an old S10forum.com thread that said Chevy LUV header might fit, so something else to look into. Good Luck!

 

IDK about this one, does yours have square ports? A lot cheaper if it does.

Pacesetter Headers 1981-1992 Isuzu Pickup, 1976-1983 Chevy LUV Pickup 1.8 2.0 2.0 (Square ports)

Pacesetter Headers 1981-1992 Isuzu Pickup, 1976-1983 Chevy LUV Pickup 1.8 2.0 2.0 (Square ports)

www.bolomotorsports.com

 

This is the Pacesetter round-port header, discontinued but used or old stock might still be kicking around:

Performance Header PaceSetter 70-1105

Find PaceSetter 70-1105 Manufactured using mandrel-bent, 16-gauge mild steel tubing and port-matched, CNC-machined, 3/8 -thick head flanges. They are designed for the best combinati ... 1976-1976 Chevy Luv Pickup Mikado 1.8, 1976-1976 Chevy Luv Pickup Base 1.8,

www.sfxperformance.com

 

Old website, has all the specs for both square-port and round-port headers; you'd have to call to see if they still can get 'em:

Import Performance Parts - Pacesetter Isuzu Headers

Buy Pacesetter Performance Headers - discount prices! Get high performance Isuzu headers, engine kits, pistons, rods, flywheels, crankshafts, camshafts, gaskets & more. We ship worldwide.

importperformanceparts.net