You didn't mention the brand but if you happen to have Aldans the springs are identified by a painted color band on the end of the spring. Naturally that means you have to disassemble the coil from the shock to see it. I don't recall the colors but I'm fairly certain that a green band is a 180LB spring. There's black, red and some others. Check Aldan's website.
If they're not Aldans...sorry, can't help ya.