Subframe first then the tower brace. Just don't run it hard without the tower brace cause you will bend the frame.
1968 Coupe <53000 miles on her 289 came off the line Jan 21st 1968. I bought it in 1983
2013 Shelby GT500 Born 12/06/2012 number 439 of 530 in DIB and 1 of 9 with Red Stripes over the top and on the seats