Tilt window balance

Could you please tell me The replacement part for this tilt window balance. It's about 20 years old, 29 inches in length, 1/2 in each side, secures with a screw not a hook, has a rectangular piece on the end that is attached to a heavy duty string which inserts into another device. It has the number 27b as well as orbsi. I also need the part that attaches to the bottom of the window. It's 2 1/2 inches long, 1inch between the screw holes, 1 in between the screw hole and the foot, the foot length is 3/8 of an inch. The last piece which the shoe fits into is 2 in. Thank you