Not sure what you meant.
Original brass or aluminum being heavier.
Aluminun is way lighter.
Brass does conduct heat better.
The new design 2 row aluminum radiators are way better then 60's tech at cooling.
If you want, i will weigh my 67 original 4 row vs my rodney red raidiator when i change cams before spring.
Just remnd me cause after lifting several of each, dont even consider using orginals any more.