Tube Identification MC275 V and VI

Hi, i have bought a new serie VI and i see differences with my old V.

MKV

V1 12ax7
V2 12ax7
V3 12at7
V4 12at7
V5 12ax7
V6 12at7
V7 12at7

MK VI:

V1L 12at7
V2L 12at7
V3L 12ax7
V4 L/R 12ax7
V5R 12ax7
V6R 12at7
V7R 12at7

I remember that the important was V2 and V5 in MKV.
which are important in the new model MKVI? V1 and V7 ?