Like any other car, Austin-Healeys were offered with several options. Some of these options are so common that they are almost regarded as standard equipment, while others are so rare that few owners are even aware that they exist. A few are worth highlighting here.
A wonderful Laycock de Normanville electric overdrive unit was fitted to the transmissions of all BN1 and BN2 series cars as standard equipment. Beginning with the BN4 in 1956, overdrive became an extra cost option. That said, the vast majority of Big Healeys came with overdrive. It operates on third and fourth gears, adding two ratios which produces six forward speeds. The overdrive increases driving flexibility tremendously. Today it is rare to find a Big Healey that does not have the "optional" overdrive, and you should insist on it. It is so closely associated with the marque that a car almost isn't a Big Healey without it!
Another optional extra closely associated with the Big Healeys is wire wheels. Like the overdrive, wire wheels were standard on the BN1 and BN2, but beginning with the BN4 in 1956, wire wheels became an extra cost option. The wire wheels supplied with Big Healeys from the beginning of production until 1961 were 48-spoke painted wheels. From 1961 through the end of production, they were 60-spoke painted wheels. Note that chrome wire wheels were never a standard option (although in a few very, very rare instances, chrome wire wheels were supplied due to a customer special order).
Initially there was no factory-offered hardtop, but since Austin-Healeys were all drop-tops it was only natural that someone would design one. Consequently, a few companies did produce hardtops for the BN1 and BN2, some of which were offered by the Donald Healey Motor Company. However, strictly speaking there were no factory hardtops for the 100. However, beginning with the 100-6 model, the factory began offering a very attractive hardtop for both the four-seat BN4 and the two-seat BN6. This factory option continued to be available for the 3000 and early 3000 Mark II roadsters (BT7 and BN7), and, although very rare, was also available for the later 3000 Mark II convertibles (BJ7) and the 3000 Mark III (BJ8). The hardtop for the BJ7 and BJ8 was a rare option since few owners would go to the trouble to remove the convertible top which was necessary to install the hardtop. Today all of these hardtops are somewhat rare, and the two-seat version particularly so. They add value to a car and are a very desirable optional extra.