Window Balance marked 2740

Thanks for posting. This looks like either the S380-28 or S385-28. The only difference between these two channel balances is the 'depth' of the bottom nylon shoe. See below. Measure your old balance's shoe depth to see what matches best. In either case, for a stamp option choose 2740.

Comparison of the S378, S380 and S385 balance shoes.

It's always tough to read photos of measuring tape, since the depth perception is compressed. That said, if the shoe is any deeper than 1", then the Series 385 is the best choice. Please double and triple-check to be sure.

My pleasure. Let us know if you have further questions!