Hmm.
Sounds like from your other post you'd be needing to solve two issues: tube retention (to keep them from jostling loose when moving the amp around) and tube protection (to prevent things from smacking into the tubes).
The most recent (third) version of the Peavey Classic 30 has a guard that protects the tubes from the back and the bottom of the amp; the second version has a guard that protects the tubes from just the back, which would probably be plenty of protection in most cases. And the first version of the Classic 30 (e.g. yours) has no guard at all. There's a [listing on ebay] for this second version's guard for ~€35, and it screws into the sides of the cabinet just below the amp chassis.
As for tube retention, I dunno if Amazon will ship tube retainer clips to you in Germany, but they are available for EL84s (you'll need four) and 12AX7s (you'll need three of these), and you'll need to figure out how to attach them to your amp chassis (a rivet of some kind, I think).
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I hear ya on the sound of the Classic 30 - it was the first amp I really fell in love with: nice, saturated dirty sound, good clean sound. Plenty of volume for nearly any gig I'll play; add an aftermarket master volume knob to the effects loop, and it can get quiet enough to play at home, too. I think it would get even better for me with a different speaker.