where would i find my ecu on a 1998 Astra van 1.7d?

Hi can any one tell me where i would find my ecu on my Astra van 1.7d as i was told it was in the drivers foot well near the sill but all i have there is a fuse box would it be behind the fuse box. i would be every so grateful if someone know where it is
best regards
graham