Dutch to English Tech/Engineering Automotive / Cars & Trucks

"het gaat niet over een onderhoudsbeurt, maar over het vervangen van de dakcassette."

I'm translating customer survey comments for a particular make of cars, so it's not always clear exactly what is being referred to. I've gathered that the dakcassette, which needs replacing, is to do with the housing for the sunroof mechanism - see reference (although the cars are not Peugeots in my case).

http://peugeot508club.nl/phpbb3/viewtopic.php?f=45&t=2628&st...

I'm trying to find out what a UK term for this could be - if there is one. I've thought of (built-in) casing, housing...

Any thoughts? Many thanks.