Not an "E" body but I did the 2x3 tubing frame connectors on my '64 "B" body. Cost a total of $20. Very strong, all the welding to the floors was done from inside the car. Just the frame connections were done from underneath.



Here's the finished product from underneath.


Centerline
64 Dodge Polara 426 Street Wedge - For when I want to go fast
99 Corvette Z-06 - For when I want to turn corners