(a) Effective Date of Rules. These rules will take effect on October 1, 1973. They govern all proceedings in actions brought after they take effect. (b) Effective Date of Amendments. Amendments to these rules will take effect on the day specified in the order adopting them. They govern all proceedings in actions brought after they take effect and also all further proceedings in actions then pending, except to the extent that in the opinion of the court their application in a particular action pending when they take effect would not be feasible or would work injustice, in which event the former procedure applies.