Series Mark 40 ANSI/AAMA 101-88 MST4653/3953 Channel Balance ID Question

Hello.
One of my windows was having trouble opening and closing and so I opened it up. One of the channel balances had a broken reel system and I was trying to find a replacement balance. I searched online which lead me here. I am unsure of what model this channel balance actually is. It is 25in long (measured from the metal ends, not the plastic parts) and around half-an-inch width. I thought it might be a Series 380 or 385 channel balance but the position of the spring and the different looking attachments made me re-consider. The stamp has the number 2430 followed by "B.S.I". Any help in identifying what type of channel balance it is would be appreciated. I have more pictures of it if those are necessary.
Thanks.

Thank you for the information. I was looking at both the Series 351 and Series 390 but I hesitated as the length between the top of the channel balance and the spring was different in my channel balance compared to either the Series 351 or Series 390. My channel balance has a 2-1/8" (two and 1-eighth inch) length between the top of the metal and the spring's hook. The pictures for both the Series 351 and Series 390 make it look like there is a shorter distance between metal top and where the spring latches on. Is this just a trick of how the display pictures are? Or just a slight difference in manufacturing? The windows were installed in 1991 so I imagine there would be some differences.
On a similar note, my channel balance's foot is barely longer than 1" (one inch). I'm leaning towards it being a 15-002 since it is no where close to being even 1/16" (one-sixteenth) of an inch much less than 1/8" (one-eighth) of an inch.
Overall, I think the Series 351 is the best fit. Unless any of the additional pictures or the spring length issue implies that I have an entirely different type.
Thanks.