518 overdrive swap
Not a 518 but you will get the idea of what kind of cutting is needed. I used a gm4l80e which is slightly bigger than the 518. Fab guy triangulated the oem torsion bar crossmember into the subframe connecotrs as well as making a band out of flat stock accross the top....
http://www.forabodiesonly.com/mopar/showthread.php?t=104301