on the confirm page change:
change:
$Shipping_PackageArray[$Shipping_PackageIndex]["WeightUnits"] = "".strtoupper($yourCart->WeightUnits)."S" ."";
to:
$Shipping_PackageArray[$Shipping_PackageIndex]["WeightUnits"] = "".strtoupper($yourCart->WeightSuffix)."S" ."";
where yourCart is the name of your eCart object.