From chassis number 61504 (approximately January 1959) the 15GB type engines were replaced with the 15GD type engines. The hole for the mechanic fuel pump which the GB type engines had ( and was covered by a blanking plate ) was closed on the GD type because it was not used on the MGAs. Like the 1600s and later types these engines had a high starter position, so the backplate had to be changed , because of this the gearbox , the gearbox tunnel and the carpet also had to be changed to get everything fit. The speedemeter cable was made 3 inches longer to clear the starter motor. Between January '59 and May '59 7716 MGAs were built with this type of engine.