I haven't done it myself even though my Mark IV was in a Mark III head cabinet. I just bought a newer Mark IV head cabinet because it was easier and had the smoother tolex and leather corners that I prefer. Being a carpenter, I can say that it wouldn't be very difficult to do. Just make sure to leave enough of the wood there towards the bottom to keep the two ends from getting to wobbly. In the Mark IV head cabinet they leave about an inch and a half to keep the panel stable. They also make the cuts that come down at an angle to add more support. The neat thing is that you can mount your spare preamp tube holder on top of the remaining section that is on the bottom so it keeps it out of harms way in the back. If you want, look at the cut out in the Mark IV to get a better idea of what I am talking about. I would suggest removing the chassis before you cut it out though. A simple handheld jig saw would be fine to do the job. If you don't have one a coping saw will do just fine. Just be sure to use a blade that cuts slowly so you don't beat up the piece you are cutting out. I would also suggest drilling a relief hole in each corner where you plan to start/finish a cut. This will also give you a more finished look without having to sand your inside corners as much. Just plot out the size of the hole so that the radii of the drilled holes will coincide with your saw cuts. The whole modification process should take no more than a couple minutes to do. Of course you will want to get a can of flat black to shoot the unfinished edges with. The drying time will take about half an hour. While your paint is drying you can work on the velcro tabs. Just measure and align them before placing them. You should be able to have your chassis out, modification completed, and chassis reinstalled in under an hour. Good luck :wink:
