[BIG BLOCK JIMMY]

This is why mine won't fit: (From ORD: '72 and older with big block motor in the factory big block position may have interference between the crank pulley and box brace, you need approximately 3" from the crossmember to the pulley for the brace to fit.)
I emailed them, DIY4X and some others inquiring about a custom built beefy, front cross member.
The attached pic is not my truck, but mine does have the factory gear box reinforcement as shown.