Their numbering on these factory springs is strange, on the springs they install on aftermarket units you can decode the numbers as follows. But I don't see there only being a 1lb difference in the upper and lower spring on these. The last number being a 1 or 3 might just be what color it is??
FOX coil-over shocks only use quality, high stress race springs. The springs are a shot-peened, heat-treated chrome-silicon material, designed to give maximum travel and minimum weight. They are preset to ensure they don’t sag over time. TIP: The springs are typically labeled: XXXX-XXX-XXXX For example: 1200-300-0350 The first four digits indicate the spring free length: 1200 = 12.00 inches The middle three digits indicate the spring free internal diameter: 300 = 3.00 inches The last four digits indicate the spring rate: 0350 = 350 lb-in