My question is. Will the stock 56 frame support a big block with out boxing it? the motor is stock, the ladies at Mid Fifty said that the frame is plenty strong enough. Not that I don't trust the gals there, but I don't want to do a whole bunch of work and find out that it is weak. 2nd opinions are always best. All of my motor mounts are Mid Fifty products. I also read that if your not using a mustange II front you don't need to box it as to allow for frame flex. any insite would br great thanks  

If you are worried about flexing just box a foot or so at the motor mount area. Its realy simple just cut the plates so they fit between the rails set them in about 1/8 or 3/16 and run a bead along the edge. The stock fram should take the big block fine. The old frames are designed to twist and flex. If you go to modern suspension you want the sports car feal you have to box  

i bought a hemi powered 56 last year while in the states, when i pulled the truck down i was amazed at how badly the frame was cracked, just boxing the front will not stop anything other than cracks around the engine mounting points  

Them frames are 52 years old and you will find a lot of the stock frames cracked. It just depends on how they were used through the years. Thats way they make a lot of X and K members. The best is to box the hole frame, and use K members. Especialy if you are going independit suspension. Thats were a lot of vehicales fail because they just want to through a motor in and get it running.So any kind of boxing helps and should be done at least from the front axel to the trans mount. Like you,you don't realy find it until you tear it down or work on it. All pickups until the last couple of years had open frames that were made to flex.