I had this set of Snap-On extensions in my old Toyota 4x4 emergency tool kit for around 10 years, but with the exception of the 4.5" extension, never actually used them. They are in near new condition, with no rust or chipped chrome. The shaft is smooth (not knurled, like the latest version), and is 1/2" o.d. Lengths are 3", 4.5", 6", 8", and 12".
A set of 5 extensions direct from Snap-On would cost around $120. I am asking $45, plus actual shipping costs. I prefer payment with a USPS postal money order. Sorry, I don't do paypal.