They are both very close to 5 mm. It was difficult to measure the used OEM one because it is in place, but it seemed awefull close to 5 mm, so, with the wear issue out of the way now, something else is making the pulley standoff gap too great. I went to see a machinist friend and he showed me a shaft collar and said they were available at McMaster dot com, so I took a look and they have an extra wide shaft collar that may be what I need to enable me to attach a puller to the pulley and get it off of the shaft. It was a two piece collar however the insides were smooth and not grooved.