I have a blockage of 60 to 70% on the left side of my neck. Can a stent be used on this blockage?

Depends. If you have < 80% blockage and have not had any mini-stokes or full blown stokes (a symptomatic), then medical management is the best way to go. This means Aspirin or Plavix (clopidogrel) with statin therapy (cholesterol lowering). If you have had symptoms, then you are better treated with an operation. Currently the use of stents is being debated and only approved if you have a "hostile" neck or bad heart dz.
May not be indicated. Assuming you talking about carotid artery, no intervention is indicated if you have no symptoms.
Perhaps. The criteria to intervene on a carotid stenosis are well known and clearly published. The gold standard for intervening on carotid stenosis is the carotid endarterectomy. A carotid stent is mainly a procedure for those patients that have a significant contraindication to having surgery.
If symptomatic. Otherwise need to follow with ultrasound until it reaches 80% or greater. Please take Aspirin if ordered by your doctor. No smoking. Take BP meds and statins if ordered also.