front end shimmie between 65 and 70 miles per hour

Loose front end suspension component or worn part. Check ball joints, struts, tie rod ends, etc. Something is either loose or worn out.

When the shimmie is not present under that speed and goes away above that speed is almost always tire related. My recommendation is to have you tires inspected by Discount Tire, Balance as/if needed. Then if you still have concerns it will need inspected by a repair facility