No contradictions exist with these plates. I'd need to see the full details to see if all belong together but a 9/75 build is a 1976 build in GM world.

All V8 HJ utes and vans are 2200kg prior to the introduction the second Sandman specification (XX7) and the XU4 normal comercials later in 1975. The "normal" or if you like "original" Sandman with commercial tyres existed for the whole of Sandman availability from early 1974 to late 1979. The second package with the lower GVW wasn't available until late 1975.