I can't tell from those terrible pictures but I think that's a metal plate JMP, too.
I was thinking that too but im not so sure... Notice the polarity switch by the standby? the 4 speaker outputs? Those more say plexi than metal panel or jmp.
Not say it is a plexi but it just has me scratching my head. Ive seen jmps with the 4 speaker outs but they seem to be pretty uncommon.
If its a plexi he might get the 4k... 6k is crack head thinking. Metal panels closer to 2.5k
; the early international (multi-voltage) amps and the later PCB amps didn't have the switch.
The canadian amps are seen sometimes with the polarity switch also... even into the later era when the rocker switches were standard elsewhere.
Its hard to make definitive rules about 70's era marshalls, they were assembled from whatever they had on hand on the time. Its not hard at all to find a mutt amp that came through with a mix bag of features.