[Beastmaster]

The list of common vs. uncommon parts are too huge to mention. Here's a short list of parts that are interchangable between Civilian and Military versions.

Some Common parts:
Frame Rails
Body tub
Hood
Bumpers
rims
tires
basic engine block
geared hubs
halfshafts
differentials
primary gas tank
suspension parts
A-Arms
Springs
Shocks

Different parts:
Electrical systems (Civilian is 12v, Military is 24)
Engine Computer (Military generally has none except for the uparmored M1114, Civilian has an engine computer for Emissions control)
TurboCharger (military is generally naturally aspirated save for uparmored versions)
Seats (Well paddded Civilian seats made by Isringhausen, Military is...well, military spec hard seats with minimal padding).
Interior (Military is spare with no noise control padding, Civilian is vinyl with some noise control padding)
Steering Column (Military is straight and non-collapsable. Civilian is collapsable. They are interchangable)
Decapitation brackets (little L Shaped brackets near the windshield frame. Designed to prevent the hood from detaching the upper torso from the rest of the body. Civilian trucks have them, Military does not)

I can (and have) interchanged military parts with my Civilian truck. Works fine. Unless it's electrical or engine computer based, I can pretty much put interchange parts.

It sounds like you have a Civilian H1. Post a pic of the outside (aim the driver's side corner) and the inside (driver's seat and all the controls) and we can verify it. If you post the VIN, I can definitely tell you if it's an H1 or a HMMWV. Civilian trucks will have a VIN plate on the driver's side windshield/top dash area.

Both the H1 and the HMMWV both come off the same assembly line for 2/3'rds of the assembly time. It gets split off towards the end to become either a HMMWV or a Civilian H1.

-Steve