Topaz rear springs

Hi,
Jacked up the rear offside of the Topaz the other day and the spring fell out, the top coil had broken off. It stays in place with the weight on it but needs a couple of new springs. It looks like an easy job to replace them but finding the right ones is harder. I'm not sure if the Topaz uses standard lwb van springs or the heavy duty ones or some other. Prices seem to vary a lot, I don't want to pay over the odds but don't want cheap quality ones that will need changing again shortly. Anyone got any advice on these.
Cheers,
Ken.

Hi I just renewed my leaf springs  on my 1996  symphony through Jones Springs, they also do coil as well , renewed shocks as well from different source but found out  from peogeut that the van was just the base lwb with normal fittings, which the converter just added to, hope this may help, Alex