Thanks for the advice chaps I will get hold of a subframe and find a welder. Don't think my skills are up to it!
Practice practice practice dude, if it doesn't work you can always grind the welds out and start a fresh, just make sure you penitrate like hell!! Don't want any protruding welds,
Also drill the ends of the cracks out to stop the crack from carrying on, then fill the drilled area with good weld
Check yoofs thread for his chassis leg modification, he used tubeular steel, Ryan used sheet steel and made a triangle like box from it, either way it will be a billion times stronger
Might be worth stitch welding a few stress areas too, like the gearbox mount etc for peace of mind
and possibly where the steering rack goes as that flexes really back, once we stitched Ryans one up the differences where amazing!! No movement at all!!