Fiesta Mk7.5 Zetec S Look-a-likey

[MGBGTMX5]

WooHoo, son gone to Uni. That means the ‘learn to drive’ 2015 Race Red 100bhp EcoBoost is all mine. (Only fair, I did pay for it.) Bought myself a bigger ST style rear spoiler, black honeycomb rad grille, and gloss black mirror caps. Want to change plain black insert rear diffuser to the Zetec S style. Anyone know if I have to have the rear bumper corner caps to add that type of diffuser? What I mean is do they extend the depth of the rear bumper to meet the bottom of that style of diffuser? Ebay surfing-research of breaker offerings suggests not. I could take a trip - with a tape measure in hand - to the local Ford main dealer but was hoping to pull on this oracle first. Thx!