The General Dynamics Defense Systems HMPT-500-3 transmission, covered in the previous entry, is coupled to engines with an input up to 447 kW (600 hp).

Using the same technology, General Dynamics Defense Systems developed the HMPT-1000 automatic transmission as a private venture.

The HMPT-1000 is a compact, low-profile alternative for the self-propelled artillery systems and other medium-sized armoured vehicles. For trial purposes a power pack consisting of a Mack E9 diesel, HMPT-1000 automatic transmission and a new cooling system, was installed in an M103 heavy tank chassis to give a gross vehicle weight of 45 tons (US).

The HMPT-1250-EC transmission, a growth version of the previously built and tested HMPT-1000, allows a significant weight and size reduction compared to conventional 55 to 64 tons (US), 1,000 hp to 1,250 hp combat vehicle transmissions.

The transmission is a transverse mount and early in 1995 was selected as the transmission for the US Army's Crusader programme which is the US Army's new Advanced Field Artillery System (AFAS). For this application the transmission is coupled to a British Perkins Engine Company Limited CV12 diesel rated at 1,500 hp. It is expected that up to 824 Advanced Field Artillery Systems and its associated Future Armoured Resupply Vehicle will be procured by the US Army. The Crusader test bed ran for the first time in mid-1999.

All transmissions utilise an advanced digital electronic controller that automatically adjusts the transmission ratio to operate at the most efficient engine speed based on throttle position and vehicle load. All transmissions are readily adaptable for a variety of engine inputs by incorporating simple software changes.

Selected for the Crusader programme early in 1995. The transmission is now in full-scale development. The Crusader is a 60 month demonstration/validation programme. The HMPT-1000 was built under independent research and development and will be demonstrated in an M1 MBT as part of the US Army's MIPS (Medium Integrated Propulsion System) programme.