Spyder RSC 1

[Joff Sibun]

First time post now I have my 72 Sprint all over the garage floor. First of many questions...
The car has a Spyder chassis bit it would appear has a very rare RSC 1 setup. The spring is mounted to the centre of the lower wishbone and goes at a low angle to a mount on the chassis. The chassis upright is serving no function other than for the top seat belt mount.
Does anybody have any information on this setup ?