Is it just the rear arches that differ?
Guy I was just responding to the body question.........In the case of my car was always Stradale interior and soft round arch gp 4 body.......
No. (sorry Tim!) the interiors differ too. Some Stradales that have been converted to Group 4 spec retain their Stradale interior but there is a specific Group 4 dash. However some Group 4 cars are converted but retain the gauges from the Stradale dashboard, all being electrical gauges (except the speedometer). The Group 4 gauges are all mechanical except for the ammeter and fuel gauge.
Guy