I couldn't tell you. Like I said, my buddy designed the board and I don't know what the reasoning was. It was 20 years ago.
The board operates off a 9v battery and the solenoids are 5v, but some have slightly bigger coils. They're only getting hit with power for like 6-10ms. and I believe others have just fed them 9v instead of regulating the power.
Someone over the years had suggested that this would be a much better option than the 355.
Suggested
From comparing the datasheets, it looks like it has higher current and better stats overall. But like I said, I'm pretty clueless.