James...I put a mc & booster in my '42...my application is a little different because I also switched to a T5 tranny. Consequently I had to mount a different brake & clutch pedal set-up (from another truck) since the original pedals mounted to the stock transmission case. However, I did mount the mc & booster (7") to the frame rail...key considerations were make sure the brake rod from the pedal is a straight shot and that the mc & booster are supported (braced) on the frame rail so they don't torque when you apply the brake.
