I ran across this on the gear page...a post by Steve Kimock relating to cab construction and talking to Jerry about it...Mar 4, 2014
"Quick Jerry Garcia story as relates to cab building and this thread. .
I did a bunch of speaker and cabinet related experimentation years ago, pretty nit-picky stuff, materials, dimensions, speaker mounting, lots of various baffle board minutia, every possible detail, just to see where it might take me.
I ran my entire program past Jerry, to see if he'd have anything to add, and at the end of my rap asked him "what are your requirements for a speaker cabinet?"
He said, and I quote: "It just has to be heavy enough to hold the speaker".
That's it. If it doesn't collapse under its own weight or fall over, and the speaker doesn't fall out, you're good to go.
The Hard Trucker's stuff back in the day was obviously overbuilt to withstand the constant rough handling of touring, but no more so than that. Just real solid, no BS construction.
The particulars of the design dimensions for the multiple 12 inch guitar cabs were just "Twin Reverb on its side without the chassis", extrapolated up to however many drivers tall the thing needed to be and deep enough to not fall over.
So, no super secret fairy dust there. Just two Twins stacked sideways sturdy enough to hold a couple JBL's and deep enough not to fall over.
So yeah, you can build that yourself or have any decent local woodworker build it for you.
I have a beautiful 2x15 JBL guitar cab similarly constructed by my local woodworking guy, and it came in around 200 bucks for materials and labor.
Nothing wrong with that if you don't have the scratch for the Hard Trucker cab.
They are pricey."