I have a pair of these Welborne Chassis-2 boxes in Alder. They were originally for the DRD 300B amps and have the back side routed out for the connector panel. They are 10.25" x 13" x 3" outside and they include a set of new, clean, unpunched aluminum top and bottom panels with the corner holes drilled to match the 8-32 threaded inserts in the box. Replacement back panels can be ordered from Welborne for either $5 or $12 depending on which one you want (or of course you could always make your own.) The top panels are .090 and the bottom panels are .060.
Now the bad news -- I originally attempted to oil these with what turned out to be some bad tung oil and the resulting finish is very uneven and blotchy. You would either have to sand or plane the surface a bit and re-oil it, and with some work they can be nicely finished again.
These boxes sell for $102 each (with the aluminum panels), I'm asking $85 for the pair, and that's shipped and with no paypal fees.
Thanks for looking,
Jim
P.S. -- Selling because I need the larger box for my project (tube rectified Dyna ST-35 clone., which I was originally going to build as a 2 chassis design using these boxes.)