Fender frame? What is this called? - Fabrication / Welding - HybridZ

Trying to find out what this is called. Obviously needs some correction and replacement. I have also been looking through threads regarding chassis stiffening hoping someone has reinforced this and could offer advice on how to repair this if i cannot source a replacement

JORMSPH Fender Compatible with Base SL SR S Hybrid SE

Datsun 240z 260z 280z Canada Bonjour, je possede un différentiel

ubergumgum's Content - Page 2 - HybridZ

ShibataFenderTeam Fender System – Lee Composites

Blue foam for fiberglass mold ? what is it - Fabrication / Welding

Not Miata) Generic Datsun LS build (Zelda) - Page 2 - Miata Turbo

Not Miata) Generic Datsun LS build (Zelda) - Page 2 - Miata Turbo

Rubbing Profile Radial Fender H 52 mm - Radial Tessilmare profile

SoCal: what is the reasonable price to weld 2 baddog frame rails