ZU-23-2s mounted to the backs of MT-LB is a fairly common phenomenon. In some cases, it may be a purpose-built model (MT-LBM izdeliye 6MB5); in others, it appears to be a field expedient battlefield modification.
Although not strictly-speaking "Franken-AFVs", because nothing significant is being added, only taken away, I think you'd see a lot of tank and IFV hulls with the turret removed (due to irreparable damage/lack of spare parts) serving as ersatz APCs in the later days of T2K.
