SAT tested layout in which the engine was mounted transversely in the back in a 1965 introduced bus chassis prototype B-65 which also featured independent front suspension. SAT started partnership with the British coach producer Metro Cammell Weymann. The companies aimed to international market and a prototype was displayed in Geneva and London Motor Shows. Only few units were finally built on Sisu B-76 chassis. In 1967 SAT introduced Sisu-Panther bus chassis types B-53 and B-58, made jointly with Leyland. The chassis was progressive type, partly frameless structure, which was rushed unfinished into market leading to several warranty issues. The construction principle, however, was applicable and later used as further improved in other Sisu chassis. After merger with VAT in 1968 Sisu bus chassis production was moved gradually from Karis to Hämeenlinna. In the 1970s Sisu chassis with Lahti bodies and locally built Hess bodies were sold in Switzerland. In the late 1970s SAT produced jointly a hybrid bus prototype SWS for Helsinki City Transport together with Wiima and Strömberg.