You would think so Phil. There are polybush alternatives to TR7 bump stops front and rear and sun visor clips as well as all the suspension bushes. There's a YouTube video on polybush manufacture which is basically liquid being poured in to a mould, so someone has to take the plunge to make one. I don't think our heater matrix was exclusive to just our cars.
The UK specialists sell a replacement matrix with fixed tails
viewtopic.php?f=2&t=23518&p=239732&hilit=Volvo+mount#p239732 and there's also a forum thread where a Mk1 Jetta heater matrix
viewtopic.php?f=20&t=21010 (again with tails) is an almost direct fit for about a third of the price. Replacing the matrix in the heater box is a hell of a job, all those rivets having to be redrilled and replaced in a dodgy plastic box. Use the sharpest of drill bits or the plastic melts, I found out the hard way. Replacing only the rubbers and replacement ss heater pipes was a lot easier. I'm not aware of the matrix failing by itself, just the hardening rubber bushes being lifted off the steel pipes as they rust away.