Nice trial. In legal jargon, this is referred to as a reversal of the burden of proof.
Please excuse me politely and politely, the 1980 claim is yours, without any proof. But, according to you, by a very experienced person. I don't want to doubt his knowledge, but there is a picture of the vehicle with a Basel license plate that was taken in 1979 (see attached picture with Basel-license-plate). So I doubt it was first registered in Basel in 1980. At the time as the vehicle has been sold to the current owner, the year of production has been stated with 1976. I would really appreciate some evidence confirming it was built in 1980.
With reply #6, you corrected me, that the 'B' on the radiator grille, never stands alone. Ever with another letter. Furthermore you stated, that with the 'D', there are minimum three letters on the badge.
But sorry, it isn't. See my previous proofs please. This vehicle wore three subsequently modernized radiator grilles. One with the badge '5 DF', one with '330' and one with '330B'. Never with a second letter.
Further:
You indicated 'by Metz' in the puzzle-designation. The turntable ladder comes from Metz. But some sources mentions, that the vehicle body was built at Frech-Hoch in Switzerland