wikipedia:De Dion tube is a non-IRS rear suspension, but with very low unsprung weight. It can be adapted to all Datsuns. De Dion is an inexpensive alternative to IRS. For roadholding and sheer cornering, it has no advantage over a carefully setup live axle, but potentially will have better ride quality due to low unsprung weight.
IRS rear end using Volvo De Dion rear
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