HX engine number, is this corrrect?

[Grunt]

I have a 1976 HX Sandman 308, m21, GV4 07/76 build

The engine cast date is 15f6 which I think is 15th of June 1976

The engine number is QT7697**

Could this be the origional engine for this van? There is a months differece in engine, compliance but during manufacture a lot happens in a month

The chassis is AHX


any info is appreciated