2001 f-450 abs/speedo issue

I have a 2001 f-450 with the v-10. A week or so ago the abs light came on for a couple of days then went out. The other day the light came back on and the speedometer started jumping all over the place while driving. The abs seems to be working properly. Could the two problems be related? Could it be a wheel speed sensor issue, if so where are the wheel speed sensors located?

the wheelspeed sensor is located on the top of the rear axle you will see it above the yoke these years have had troubles with this parts

Thanks Big White Bufflo. I hope that the two issues are a result of the one part (wheel speed sensor) Doesn't that sensor get it's signal from a gear that is bolted to the ring gear? I hope that the issue is not inside the housing.