the b206 is a version of the b204 but without the dual balance shafts. it was only offered as a naturally aspirated engine b206i producing , seemingly a europe-only option in 1994 non-turbo 900 ngs. this engine is popular among saab tuners in sweden (e.g. trollspeed) due to the lack of balance shafts but with presumably equal strength as the turbo blocks with balance shafts.