Sill panel for rear wheel, right | VintageDub

Sill plate for rear wheel, right, Top quality | 251 831 108

This sill plate is the right rear of your T3, where the wheel arch connects. The replacement part (251 831 108) is prone to rust here, so this replacement is a good opportunity to do a clean job. This is a visible part when the car is stationary, so its appearance matters. Combine this with the left sill plate, and you'll have tidied up the entire rear wheel area nicely.