Kirley,like you,I have drew a blank with my reference material also,although the wheelbase for all the oil tankers appears to be 12'.The oil tankers you are doing look similar to the old Burmah tanks and given the donor chassis recommended for use,this chassis is for a 12'wheelbase,20 ton British tank wagon,then with the work that you have done with the tank ends being close to either end of the chassis,it looks correct to me.Good job with the tanks,they look the part and look right and I certainly do not see the need to do any modification to them.Well done