Hello there!
Thanks for reaching out to us. It looks like you have the Series 795. However, it appears your balance uses a hook for installation which means this must be a custom order. To outline it for you, we'll take the S795-32 with the 32D stamp and swap out the default screw tab for the 15-198 hook. You will also need the 15-229 due to the blue brake in your old T-lock shoe. Note that this part is sold separately and you will have to swap it with the default shoe the S795 comes with. These parts just pop on and off as shown in the video below.
What I will do now is email you a purchase link and price quote for (2) balances that you can use to place an order on our website.
I'll be here if you have any questions!
Sure, you can install your old hook onto the balance though it can be a tad tricky. You will need a bench vice to securely clamp onto the cord so as to make sure it doesn't snap back into the pulley while you swap the clips out. These cords are under a lot of tension and if it gets away from you then it could potentially ruin the balance; if you aren't careful, it can also take out an eye. If you proceed with this, make sure to wear safety goggles and gloves, just to be safe.
We also recommend replacing the balances on both sides of the window. You wouldn't want to pair an old balance with a new one. That would cause the new hardware to wear out a lot quicker as it'd have to pick up the slack for its older counterpart.