Obviously there are two different specs, 88 and 90. But did ford put the 90 spec interior in an 88 spec car on the change over year (89 late F, early G plate)?

 

Yes they put the zolda trim in 89 f plate cars, prefer the Daytona trim myself

 

They presumably had loads more 88 spec rear spoilers left over, as didn't they use those on the Escort Eclipse/Equipe whichever it was?

 

89 spec S2's which are on late F or early G plates are the crossover cars - the outside retained the "88 spec" front bumper & rear spoiler but the interior was generally "90 spec" light grey Zolda trim with a few more differences - some have rear interior lights some don't etc.