745 vs. 782 – Your experiences / recommendations

Hello together; I am supposed to work on the topic of changing bridges and in principle have no idea about this topic: Which of you professionals can help me: – When do I take 745, when 782 ? Why do you take one or the other ? – Which wheelbase does it need ? – Digger or tandem trailer ? Maybe someone can also tell me where I can read information. Thanks ThomThom01