Original sentence: Other locomotives that may have exceeded the 126 mph (203 km/h) record include the Pennsylvania Railroad's mighty S1 prototype which is rumoured to have reached 140 mph (225 km/h), although the claim is disputed,  and the Milwaukee Road class F7
Edited sentence: Other locomotives that may have exceeded the 126 mph (203 km/h) record include the Pennsylvania Railroad's mighty S1 prototype which is rumoured to have reached 140 mph (225 km/h) (but these rumors are extreamly doubtful) the Milwaukee Road class F7