Parking brake return spring

[Jimal]

This is one of the fiddly little things I want to fix before putting the bed on. After overhauling the brakes on my K-10, I'm happy to report the parking brake now works on my truck. Or at least it holds the truck when on. As you can see, I'm missing the return spring. I'm sure something off the shelf should work if I make up a bracket to attache to the lever and drill a hole in the frame. Any suggestions on the size (length, diameter) of that spring?