Searching for 25 4 en Caldwell

Thanks for posting. At first glance this looks like a Series 350; but I suspect the top fitting on the balance in your photos might be damaged and missing wings, or side tabs, like the bottom fitting has. Compare to an undamaged version of this balance if available. If it turns out both fittings have wings, then you need either an S385-26 or S380-26. The only difference between these two balances is the 'depth' of the bottom nylon shoe, so compare both with your old hardware to see what matches best. You'll need a stamp option of 2540.