Oh it is indeed the 100B (same as I have) - you can see it on the cooling fins behind the metal grille, these are for the dummy load which only comes in the 100B.
As this is a very rare model (there were approx. 100 made until 94) I assume he's gonna swap it for a 20th Anniversary one - cannot imagine someone who tours like him has an amp in his rig where there are no backups available.