https://www.ebay.com/itm/rawcabs-boogie-Mark-III-long-pine-Black-dot-head-cab-with-reverb-tank-cutout/303356760021?hash=item46a178cfd5:g:3HEAAOSw9PxeG1u9
Just tell him you want it for a MarkIV and he'll make it. He will make a higher quality shell if you want with dovetail joints and exotic wood.