GTE mk2 Rear headrest problem

[GTE Mk2]

Fitting rear head rests last night in the GTE mk2, got a problem!

The plastic securing tubes that the headrest metal bars slide into wont fit into the rear seat backs. I punched through the cloth to find the holes, but these fittings originally from front seats wont go in. So im assuming there are different plastic fittings for the rear head rests? Can anyone help?
Cheers

[Ed]

I didn't know any Mk2 GTE ever had rear head rests?

[Benn]

Are you using proper rear ones? Or fronts? As you'll need proper rear ones.

[Astra Dan]

The CD Mk2s had rear headrests. Rare as anything these days. This is the only way to do it properly. You can try cutting down the front sleeves.
Some Mk3 Astras had rear headrests, too, but from memory these don't quite fit the Mk2s seats.