With the replacement T5 box (ex TVR) we designed a new mounting from box section, cutting out one face to form a C-section so it could slot over the existing floor box sections, which in turn were drilled and strengthened with tubes before bolting in place.
'Tina originally came to us with a simple swing-axle purely designed for the drag strip.
We have fitted Escort rally spec single-leaf springs with adjustable anti-tramp control arms and for now just removed the coils from the coil-overs to use the Gaz shocks. As well as strengthening the chassis mounting areas, heavy-duty shackles we made.
The ride height looked about right at first, but after a few miles for things to settle, it's probably a bit too low at the back, though the sill is parallel to the ground?