Given that you have used the term Hanomag, i am guessing you have the old Ausf C kit.
Its not a very accurate kit, but it does look like a 251 and it is the riveted version of the Ausf C. Leave out the drum between the 2 front seats. That was a water tank and only fitted to the /8 Ambulance.
There were, by my reconing, 63 variants and versions of the 251. About half can be bought in kit form.
I am a Norfolk man and i glory in being so
On the bench: Airfix 1/72nd Harrier GR.3/Fujimi 1/72nd Ju 87D-3