It looks as if my ZROCK2 parts pull date is within a few days or weeks and I’m still wondering whether or not to go with the tube regulation mod.  I’m actually not sure what it is or what it does.  Is this particular mod one that adds an internal tube—one of those “lifelong” tubes—or is it an external tube?  I don’t recall ever seeing a ZR2 with a second tube on the outer case.  I will be going with all other available upgrades, but would like some quick advice on the tube regulation mod.  

Doug, take a look at the older thread "Annimversary Mods for the ZROCK2." The voltage reg tube is interior to the chassis.