You need a Colt marked M7 bayonet that has the extension on the handle.
Ah so the German ones were different? I'd have to check mine - but I think it was made by Ontario Knife Co and marked Colt. Looks like I'll have to find a German version now lol
Correction - I guess mine was made by Imperial:
http://worldbayonets.com/Bayonet_Identification_Guide/m4_thru_m7_series/m4_m7_series_p2.html



























