Initially the models were fitted with a small vertical rear flange that located within the boot. This was changed in 1986 to a 2 x 9mm horizontal flange. At the same time the DG18-19 baseplate text changed to DG18-19-22 followed by DG18/19/22/24/25 in 1987. A steering wheel was added in 1989. The baseplate text changed again in 1990 to read 18-19-22-24-25-38.

The tab on the front ladder mount was removed shortly after introduction to aid assembly. As with the DG10 this model type came with thick and thin wings. The holes and pins where the plastic figures were located was removed in 1986. A turntable ladder was introduced in 1988 using the large wheels from the DG04. In late 1989 the baseplate DG10-12-34-35 was introduced.

The tab on the front ladder mount was removed shortly after introduction to aid assembly. As with the DG10 this model type came with thick and thin wings. The holes and pins where the plastic figures were located was removed in 1986. A turntable ladder was introduced in 1988 using the large wheels from the DG04. In late 1989 the baseplate DG10-12-34-35 was introduced.

The tab on the front ladder mount was removed shortly after introduction to aid assembly. As with the DG10 this model type came with thick and thin wings. The holes and pins where the plastic figures were located was removed in 1986. A turntable ladder was introduced in 1988 using the large wheels from the DG04. In late 1989 the baseplate DG10-12-34-35 was introduced.

Some of the original baseplates had thinner axle covers and lacked the triangular support to the rear axle, these variations may have only appeared on the Worldwide Collectors Club model (DG21001). In 1987 the baseplate was changed to read DG21-26. Steering wheels and seats were added in 1991 and during 1992 the baseplate changed to read DG21-26-51.

Number 1 or 2 can be seen on the nearside of the baseplate, this refers to the mould the factory used at the time of casting.