Eventually a reasonable Chevrolet Impala Fire Chief #482 came along. This is the second type with the chrome running through the middle and supplying the grill and rear bumpers and light surrounds. Both models sold in similar quantities but the old one was replaced after two years and the second one lasted for four years.
Apart from some dog grooming van version which I can hardly bring myself to search for never mind buy, that should complete the Impala stock.
I must get a badge for the old one as those white doors look wrong as they are.