[tss240zg]

Thinking of doing a rally design coilover conversion
I was told by s13eater to get a 2 and a quater threaded tube....grind the spring cup off the std strut and weld it up. But can this be done at the back as springs and shocks are separate.... Spring is free so it is not a strut... So what should i do.
Any help appriciated
Thanks
Tss240zg