some minor variations with the super fast concrete truck as some also appear with rw version.
different rear, most notable the chute sizes.
http://img49.imageshack.us/img49/6290/concretetruck21sfcastake7.jpg
http://img57.imageshack.us/img57/566/concretetruck21sfcastdrg5.jpg
different sizes with the side equipment and controls, wide and narrow ladders.
http://img50.imageshack.us/img50/1736/concretetruck21sfcastcer2.jpg
http://img50.imageshack.us/img50/6312/concretetruck21sfcastbkr2.jpg
different size emblems, the right one looks a little worn
http://img50.imageshack.us/img50/7336/concretetruck21sfcastd1df6.jpg
dark and light yellow cabs.
http://img236.imageshack.us/img236/9764/concretetrucksf21colorstk3.jpg
http://img57.imageshack.us/img57/7693/concretetrucksf21pairbxki1.jpg