On further internet research, I think the difference in reported span of the F-16 is due to measuring the span with or without the wingtip missiles.

Whilst none of the list below is a formal declaration of information (from the web, so must be true), and there are slight variations in the numbers, I think the consensus is there;

Wingspan for all F-16 variants from initial A model onwards (excluding XL) was;

Without tip missiles: 31'0"
With tip missiles: 32'8" - 32'9.5" (missile type not specified)

The basic wing size appears to be constant across all variants.

F-16.net

F-16A/B Dimensions: wingspan 32 feet 9 1/2 inches, length 49 feet 3 1/2 inches, height 16 feet 8 1/2 inches, wing area 300 square feet.
F-16C/D Block 25 Dimensions: wingspan 31 feet 0 inches, length 49 feet 4 inches, height 16 feet 8 1/2 inches, wing area 300 square feet.
F-16C/D Block 30/32 Dimensions: wingspan 31 feet 0 inches, length 49 feet 4 inches, height 16 feet 8 1/2 inches, wing area 300 square feet.
F-16C/D Block 40/42 Dimensions: wingspan 31 feet 0 inches, length 49 feet 4 inches, height 16 feet 8 1/2 inches, wing area 300 square feet.
F-16C/D Block 50/52 Dimensions: wingspan 31 feet 0 inches, length 49 feet 4 inches, height 16 feet 8 1/2 inches, wing area 300 square feet.

Af.mil
Wingspan: 32 feet, 8 inches (9.8 meters)
Length: 49 feet, 5 inches (14.8 meters)
Height: 16 feet (4.8 meters)

sky-flash.com

F-16 A: Wing span: 10,01 m.(over missiles)

http://www.iaf.org.il/645-en/IAF.aspx
Wingspan - 9.45 meters, With missiles - 10 meters.
Length - 14.93 meters.
Height - 5.10 meters




Paul