Cadwell block and tackle

This appears to be either an S380-24 or S385-24 Channel Balance. 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 2340. 

It's a bit tough to tell from pictures of measuring tape. If it's 1" or just a little less, I would say the Series 380. If it's at all bigger than 1", even by less than 3/32", then it's the Series 385. Keep in mind the old shoes can wear down from use over time. 

Comparison of the S378, S380 and S385 balance shoes.