Hi, Lucandhar,
I'm no expert so this advice would have to be verified. But on a machine without clutch the drive belt would come from the motor shaft in a straight line to the brush bar pulley. Whilst on a clutched model the first belt goes in a straight line from the motor spindle to the clutch drive pulley whilst the second belt goes from the driven pulley of the clutch to the brush bar, thus the two belts are offset. Therefore, the pulley on the brush bar would have to be in a different position further along to accommodate this offset.
Cheers, SonyD20.