Mesa Boogie - Rackmount heads! We've offered many amps in rack mountable format over the years and the Mark Five: 35 and JP-2C amps are the two newest amps purpose-built for that
Mesa Boogie Mark IV - Rack Mount Head - with FU-3 Foot Switch | Reverb
Mesa/Boogie Mark VII Rackmount Tube Amplifier Head | zZounds