In October 1958, Abarth introduced a flagship GT car that heralded the arrival of a new twin cam 'Bialbero' engine. Known as Record Monza, it was also significant for being the last collaboration between Abarth and Zagato of Milan. The twin cam head was designed by Gioachino Colombo and featured hemispherical combustion chambers that allowed the use of high-domed pistons. This was fitted to a Fiat 600 block bored out to 747cc and equipped with all the usual Abarth goodies; special camshafts, cylinder heads, valves, manifolds, carbs and exhausts. It transformed the humble 22bhp original to one of the most potent sub 1-litre engines available. With compression set at 9.7:1 and a pair of twin choke downdraught Weber 36 DCL3 carbs, output rose to 61bhp at 7000rpm. Other trick Abarth parts included uprated springs (transverse at the front, helical at the back) and stiffer telescopic shocks. Brakes were enlarged at the front with each drum getting an extra hydarulic cylinder and a double rather than single leading shoe arrangement.

Zagato were responsible for the Record Monza's lightweight aluminium bodywork, this having a more gently rounded form than the pushrod-engined (and markedly less scarce) 750 GT 'Double Bubble'. Interesting features included a novel three-piece rear window arrangement, a large central air intake on the engine lid and Plexiglas-covered headlights. Weighing in at just 540kg, the Record Monza was capable of reaching 190kmh flat out. Unveiled at the Paris Salon in October 1958, a production run of 100 cars went ahead immediately to obtain homologation in the GT category for the 1959 season. It turned out to be a great year for Abarth with the Record Monza quickly becoming the car to beat. However, demand was far outstripping supply and held back by limited production availablity, it is believed that only around 50 twin cam versions were completed, the remainder getting single cam engines.

Chassis 556150 is one of those handful of Record Monza's built for racing with the twin camshaft Tipo 221 750 Bialbero engine (number 627182) and therefore came with a secondary identification plate (originally fitted to all Bialbero variants) denoting a Progressivo Vettura ID of A/221 115. Importantly, both these original identification plates are still in their correct positions in the engine bay. 556150 was then dispatched to Milan where Zagato fitted it with body number 43, this coming painted in the distinctive duck egg blue so popluar on Abarth racing cars of the period. Zagato completed the car, issuing its certificate d' origine on March 27th 1959. 556150 was ordered from the factory for racing by Emil Knecht of Zollikon, Zurich, and he appropriately had it equipped with oversize drum brakes, Zagato racing seats and the rare 14-hole wheels. Mr Knecht was a member of Squadra Tartaruga, an outfit comprising a bunch of Swiss privateers originally established by Rico Steinemann who later replaced Huschke von Hanstein as race director of Porsche in 1969. Mr Knecht wasted no time before entering 556150 in its first event, the Mitholz-Kendersteg Bergrennen, finishing third in class. Ten days later on May 20th 1959, he registered it for road use. Other notable results that season included a fifth in the under 1000cc class at the Nationaler Automobil Slalom.

In early 1960 the car was sold to its second owner, Jörg Oggenfuss of Kusnacht, Zurich. Mr Oggenfuss also raced 556150 and most notably that year won his class at the Sierre-Montana Crans Bergrennen in August. On April 27th 1961, 556150 was sold to Ernst Aeberli in central Zurich. Mr Aeberli was another member of Squadra Tartaruga (and friend of Emil Knecht) who raced the car over the next two seasons. For 1961 he had it upgraded with disc brakes and took class victories at St. Ursanne, Hockenheim, Mitholz and Dubendorf securing the Swiss GT Championship along the way. Established on an Index of Performance basis, Aeberli finished ahead of second-placed Heinz Schiller in a Porsche 356 Carrera Abarth and the Abarth 1000 Bialbero of Peter Ettmuller in third. In light of this significant achievement Mr Aeberli was sent a congratulatory letter from Carlo Abarth, a copy of which remains with the car. For 1962, Mr Aeberli removed the original Tipo 221 750cc engine and switched to a Tipo 222 700cc twin cam supplied by the Swiss Abarth concessionaire. That season he took class wins at Mitholz and Payerne and never once finished outside of the top three in class.