1973 360

This lists curb weight for a '70 340 Duster as 3275#

The 1970 Hamtramck Registry - 1970 AMA Specifications - Valiant & Duster

'74 Duster 360 - 3395#

The 1970 Hamtramck Registry - 1974 AMA Specifications - Valiant

And just for comarpision sake;

'73 Duster 340 - 3220#

The 1970 Hamtramck Registry - 1973 AMA Specifications - Valiant

'71 and '72 specs aren't listed.