Editing Stridsvagn 103 (section)

===Prototypes===
[[File:Strv103 Tanks During Field Exercises in Klagstorp, 1966 (GMSF.009705).jpg|thumb|left|Tank mobility trials in 1966]]
A spring 1957 meeting to consider the various designs resulted in "S" raising enough interest that a demonstration of its design features was needed.<ref name="Lindström"/> A small contract was let to demonstrate that the suspension system could be used for aiming. This led to experiments using a surplus [[M4 Sherman]] and [[Infanterikanonvagn 72|Infanterikanonvagn 103]] vehicles fit with external systems that moved the suspension. These seemed promising, so one of the test hulls from the earlier KRV program was adapted for more rigorous testing and the first application of the stabilizer. This was later modified to remove the first and sixth road wheels to a make a layout more similar to the S proposal.<ref name="Lindström"/>

As part of the ''Försvarsbeslut 1958'' (defence plan of 1958) deliberations, the [[Riksdagen]] (Swedish parliament) debated the three Alternatives. S would be the most expensive, but it was ultimately selected for the symbolic value of a domestic tank in a neutral country as well as the spin-off effects on Swedish industrial competence. On 4 February 1958, a contract was released for two prototype hulls, S1 and S2. [[Volvo]] was selected to build the engine system and [[AB Landsverk]] the drive trains. S1 used an electric motor for power, supplied by a generator trailer, and was used to test the suspension system. S2 included the Volvo-designed Diesel-turbine hybrid engine and was used to test the drivetrain and flotation system. These were also successful, and in 1960 an order was placed for ten pre-production vehicles.<ref name="Lindström"/>

By this time, the UK had offered the latest Centurion Mk. 10, which featured the famed [[Royal Ordnance L7]] 105&nbsp;mm gun. The gun had been licensed for production in Sweden and would be available shortly, so the decision was made to replace the much larger guns originally conceived with the 105 in order to save development costs. For the S, it was lengthened to L/62 from the original L/52 to allow more powerful charges to be used. Because the gun was fixed in place, with no recoil movement, the autoloader was able to reach the very high rate of firing every three seconds.<ref name="Lindström"/> This led to the production design being given the name "Stridsvagn 103", meaning the third design mounting a 10&nbsp;cm gun.
[[File:Strv 103 in 1967 (GMSF.002303).jpg|thumb|left|An early production vehicle in 1967]]
The first of these "zero series" vehicles arrived in 1963. During testing, it was noticed that while a two-man crew could operate the vehicle successfully, other tasks became more difficult. Notably, it made operating in the field more difficult because a two-man crew was not enough to perform guard duty or easily perform track maintenance or reloading ammunition. The decision was made to add a third member, assigning them to operate the radios as well as having a second set of controls and vision systems to allow them to drive the tank in reverse at high speed.<ref name="Lindström"/>

The vehicle was first shown to the public in the spring of 1963. It was an immediate worldwide sensation. [[John F Kennedy]] expressed an interest in the design, leading to a memo by [[Robert S McNamara]] noting:

{{cquote|Their new tank has advantages over our M60 in its low silhouette, lighter weight and amphibious capability. On the other hand, it is incapable of concurrent automotive movement and all-around engagement of targets. While the Army fully recognizes the advantages in the Swedish design, it considers this new tank to be more nearly a defensive tank destroyer or assault gun rather than a tank within the Army's concept of employment of tanks.<ref name="Lindström"/>}}