Hellcats received the M1A2 gun equipped with a muzzle brake, which also incorporated a faster rifling twist. M18s prior to serial number 1701 (registration number 40155577) did not have any winterization equipment installed at the factory. Beginning with M18 serial number 1701, an engine oil dilution valve and provisions for a battery-powered heating unit that drew fuel from the left fuel tank in order to produce hot air for heating the back of the engine, transmission and differential and their oil coolers, the vehicle battery, and the auxiliary generator in extreme cold conditions was installed. The network of hot air tubes was installed in the factory, but the heater power (blower) and burner units, their fuel pipe and connecting air tube, and the air intake shutter to close off the engine compartment were to be installed when necessary in the field. Beginning with M18 serial number 1858 (registration number 40145734), the original gun travel lock on the turret roof which had a swinging arm held by a fastening pin was replaced by one that had a rotating ball stud with a retaining clamp operated by a handle. In October 1944, heavier shock absorbers were introduced. Later vehicles also featured an M20 azimuth indicator next to the gunner's controls, allowing for easier performance of indirect fire missions. On late production vehicles, the towing pintle mounting was redesigned to allow it to swivel when towing a trailer over uneven ground. Combat use In July 1943, the AGF directed the Armored Board to consider the T70 for use as a light tank by comparing it with the existing requirements for a light tank. In January 1944, the proposal was rejected because it was felt that the T70 had insufficient armor and secondary armament. European Theater Initial combat in Italy Five T70 prototypes were sent to Italy in the spring of 1944 for testing and saw combat during the breakout from the Anzio beachhead with the 601st (two) and 894th Tank Destroyer Battalions (three). The 894th employed them in the battalion's Reconnaissance Company because of their high speed. In addition to the vehicle's speed, battalion members were also impressed with the power of the 76 mm gun, but were less complimentary of the T70's thin armor and small internal volume, which they felt affected crew confidence in battle, and made living inside the vehicle and handling main gun ammunition awkward, respectively. The 805th Tank