motor umbauen

[Uley fire engine]

Hi from England, I have just become the owner of a beautiful German Fire Engine, typ LF 407. I would like to know the year of manufacture of my truck, can anyone help? The chassis number is 319 001-10-003 924, motor typ M 121 B VII, nr. 121 926-10 002 017. I am also thinking about either changing the present the 1884 benzin motor for an OM 615 diesel motor, or converting the truck to gas. Any advice on this would be great. Thanks, Jamie. Now for the German version!
Ich mochte in meinen L319 von einem m 121 B VII auf einen OM615 umbauen. Was muss ich beachten bzw. tauschen?? Forward, on , Jamie.