Is it possible to put a 60\'s mustang body on to a mid 90sto 2003 mustang frame ?
The basic design of Mustangs hasn't changed that much since introduction. They are still about the same size overall, with a unibody / subframe design and rear wheel drive.
You wouldn't know it by looking at them side-by-side, but the overall dimensions including wheelbase and height / width isn't that much different now than it was since '64. My '67 has a wheelbase of 108 inches, an overall length of 183.6 inches and a 'shipping weight' of 2605 pounds.
The last mustang in my most recent 'catalog' book is the 2001 which has a wheelbase of 101.3 inches, an overall length of 183.2 inches and a shipping weight of around 3200 pounds.
My answer to your question is: you can go the 'restomod' route. Install a 5.0 EFI & 5 speed or AOD in a classic mustang and what you've basically got is a mid-nineties Mustang drivetrain within a classic shell. You could probably even fit a current 4.6 or 5.4 modular engine in there if you wanted to. All the modern accessories like power windows are available and easy to install in a '60's Mustang if you want them.
Plus, my '67 is about 600 pounds lighter than '90's through current Mustangs, so it's easier to get a good power to weight ratio. Mine averages over 20 mpg on the freeway, and is surprisingly quick even with a completely stock '91 5.0 EFI & 4-speed AOD in it.
\'67 Mustang fastback w/ 5.0efi & T5z; TCP suspension, steering & frame connectors.
2000 Explorer Sport 4x4