I thought I read somewhere that the 4th is wider (makes sense). But does this bolt in and have the mounts line up? I can always run more back spacing on the wheels or cut the rear. There is a local rear for $20 and might be a cheap upgrade.
They're wider, the upper mounts are wider-set and to accomodate for mis-aligned control arm points, you'd have to go to heim or poly-ball parts. Then there's the usual shock / spring perches to move around.