760 rear sagging - large donut tank, advice re springs
 

Hi all, I have a large donut tank in my 760 Turbo Sedan. The rear is sagging, due to the weight (I assume -as it is more noticeable since the conversion). I don't think the car was fitted with Nivomats. There are no other issues, but I would like to get the ride height up a bit, as I have some driveline vibration which may be because of the angle of the propshaft in relation to the sagging rear end.
I understand that heavy duty estate springs are an option, but not recommended. Can anyone recommend an heavy duty spring that is available in the UK?

When we do a conversion we do r ecco mend fitting the heavy duty rear springs to cope with the extra weight. I have even designed some springs to work with limos as part of a conversion from nivomat to normal suspension.