Question about window balance coil spring equivalency

I just placed order 618045 for product S190-840, a 1/2" 840 window balance coil spring. I measured my broken spring at about 1/2" wide and the screw end style matches up also. However, my coil spring is stamped with an 8, and after my adventures in Googling, my conjecture is that the spring is rated for 8 lbs. of force and this is equivalent to springs with an 840 stamping. Please do inform me if I have made a mistake and need to modify or cancel my order.

Thank you.

Thanks Paul! I think I am set for a simple replacement--I could make out the 8 stamped on both springs in the balance. Hopefully, the new spring is in the mail.

Jonathan