Are they needed and any good how to's?

 

Ford thought so. All Mustangs got the LH box in 67 (convertibles always had both) and 68-73 all Mustangs had both. Ford never spent 2¢ they didn't need to, so I gotta figure they were quietly upgrading the car. Get to 2-piece version stocked by Glazier Nolan and others, way easier to install.

 

Yes, they do make a difference.

 

what type of difference do they make? do theyfirm up the body and create some rigidity like i think they would do?

 

Yes.

Installation isn't too hard if you know how to weld. Slit the toe board extention at the frame rail, slide the complete box up and into place using the weight of the car as leverage to get it into position and then weld it all together.

 

Everyone extols the virtues of subframe connectors. Well, this turns your rocker assembly into the subframe connector.

If you really want a stiff Mustang, and I have seen this, put convertible inner rockers and front torque boxes in your coupe. That would make add-on tubular subframe connectors look really lame.

 

if I run subframe connectors do I still need torque boxes?

 

here are some pictures when i did my 69 for your reference.

good luck.
http://s258.photobucket.com/albums/h...0torque%20box/

 

I use both.

 

I have some ready to go on but its not the welding that worries me as much as the fitment of the parts.