(a) Except as provided in subsections (b) and (c) of this section, this Criminal Code does not apply to offenses committed prior to July 1, 1973. Prosecutions for offenses committed prior to July 1, 1973, shall be governed by the prior law, which is continued in effect for that purpose, as if this Criminal Code were not in force. For the purpose of this section, an offense was committed prior to July 1, 1973, if any of the elements of the offense occurred prior thereto.
(b) In any case pending on or commenced after July 1, 1973, involving an offense committed prior to that date:
(1) Procedural provisions of this Criminal Code shall govern, insofar as they are justly applicable and their applicability does not introduce confusion, delay or manifest injustice;
(2) Provisions of this Criminal Code according a defense or mitigations shall apply, with the consent of the defendant.
(c) Provisions of this Criminal Code governing the treatment and the release or discharge of prisoners, probationers and parolees shall apply to persons under sentence for offenses committed prior to July 1, 1973, except that the minimum or maximum period of their detention or supervision shall in no case be increased, nor shall this Criminal Code affect the substantive or procedural validity of any judgment of conviction entered prior to July 1, 1973, regardless of the fact that appeal time has not run or that an appeal is pending.