I think the rears can be installed either side up, I called FRPP tech and switched mine to tight colis up. I would install either both 1.0 inch or 1.5 inch, I did the 1.5's on my son's GT/CS, sometimes the back looks low. So I don't think I would mix them. The rears are easy to take in and out, so you could check both set s though. Good luck !
07 GT/CS vert, wife's car, garage queen. sold 11-30-13, going to good home, 7,785 miles.
2013 GT PREM., 500 pckg, needs mufflers...
07 GT/CS, son's car.
1971 Boss 351, mine since 1979.
68 Cougar, my first car, interviewed on Pinks All Out Takes, STL 2008, 10.40's @ 130, 399 Windsor
Son's S/C dragster, SBF 7.92 @ 165 so far......