Homegrown project ? For the people that know how to dial in a rear wheel drive suspension for drag racing this is nothing new.

When the rear end and rear seat goes back in the car you will not be able to see any of the additional bracing.

Doing these reinforcements in any Mustang is very important. Most Mustangs that run a good 60ft time which is where 90% of the body flex comes in need these reinforcements so the floorboards do not tear away from the frame. My car had actually pulled the tack welds away from the frame under the rear seats already but had not torn the floorboards yet.

A friend of mine that builds race cars and chassis did the work. He also went to the Roy Hills school of drag racing for suspension set-ups.

If you want his number let me know.