have to manually change gears at specific times, even if the tank was moving over rough terrain. The tank's weight is distributed over five double, aluminum-alloy, rubber-tyred road wheels on either side, propelled on wide tracks. The tank could ford deep water obstacles without preparation, up to with minor preparation, and up to with full preparation. Full preparation for water operations consisted of the addition of a snorkel tube, the installation of blanking plates, carried on the front of the hull, over the engine compartment's air intake louvers, and the installation of infrared driving equipment, including a searchlight. In 1969, a special diving and evacuation training vehicle, without engine or tracks, was created and nicknamed the AMX 30 Gloutte (from the French faire glouglou, "gurgle"); it could be quickly be lowered by winch into a reservoir and was equipped with an escape tube. Modernization During the production run, many improvements were implemented. These did not include gun stabilization from 1971, and from 1972 replacing the original coaxial heavy machine gun with a dual purpose autocannon against light armour and helicopters, with the ability to depress to −8 degrees and elevate to 40 degrees. All French army vehicles were eventually brought to this newer standard; the designation remained AMX 30B. Beginning as early as 1973, only seven years after the beginning of production, the French began a research program for a future modification of the tank. The project was to result in a AMX 30 Valorisé ("upgraded AMX-30"). In June 1979, the French Army decided to both build new and modernize existing AMX-30s with an improved fire control system and a new transmission, and designated them AMX-30B2s. The first new production vehicles were taken into service in January 1982. Improvements to the COTAC APX M-508 fire control system included the installation of a laser rangefinder and a low-light TV (LLTV). The main gun's lethality was improved with the introduction of a new armour piercing fin stabilized discarding sabot (APFSDS). The original engine was exchanged for an improved variant, known as the HS-110.2, producing . The poor transmission was replaced with the semi-automatic SESM ENC200 transmission (now RENK France), with a torque converter. The suspension was improved by adopting new torsion bars and shocks, which increased the vertical deflection range of the road wheels, thereby improving the tank's off-road mobility. From 1998, the French army started to replace the engines of its