Aubs I have owned 2 H1's and the 2003 is what you want at the very least. Why? 2 Words
(Eaton Lockers)

. This was a change from the Detroit Lockers on the Previous model H1'S. In addition in Late 2001 the started to make the engine in another plant eliminating most pre-2001 8 cylinder crack. Please take a look at this link for H1 model year changes.
http://www.lynchhummer.com/changes/h...ges.index.html
2003 H1 Powertrain and Identification Information.
- VIN 10th Digit designating year = "3"
- Engine: 6.5L Turbo Diesel 195 H.P. 430 lb. ft. VIN 4th digit ="F"
- 4L80E Electronic 4 speed Automatic Transmission. VIN 5th digit ="A"
- Top Speed 83+ mph.
- Approximately 477 '03 models built, 112 of which built specifically for the U.S. Border Patrol.
- New Radio face for Monsoon Stereo.
Available Electromagnetic Locking Rear Differential.
Available Factory Heated Leather Seats.
Heavy Duty Brushguard Standard.
New Color- Summit Silver.
New Color- Black Diamond.
New Interior Air Conditioning Ducts.
12 Scheduled Maintenance Services During First 36 Months Free.