Many Jaguar/Jazzmasters are pretty heavy. Not 13lbs, but still. The older ones were mostly swamp ash, which can be hefty due to that and the body size. Swamp Ash is lighter than regular Ash, but that's like saying iron is lighter than lead. Newer ones are more often Alder, which is (or can be) lighter. It's tough to predict, as wood density varies within a species, or even from the same tree. For instance, Swamp Ash is only lighter if you get the wood from the lower 6-8 feet of the trunk that's always being washed/dried as the swamp water depth changes. Makes it kinda like driftwood.