After owning quite over 60 cars in my fourty plus years I found that many IRS setups although good they can cost quite some time and money to get right. However the De Dion Alfa Romeo gtv6 and Volvo 360glt are surprisingly amazing handling vehicles from factory with little but just good shock absorbers. Leaf springs are simple and effective to setup and datsuns of the 1000 and 1200 variety are so small and compact that IRS is not really needed however LSDs are not easily afforded unless you already have a h165 rear shortened, factory fitting or fits without shortening.