The Dentron JR Monitor was introduced in 1978. (QST did a review but it’s not available in the digital archive.) There was however a review in a magazine called “Amateur Radio Today” in 1979.
This is a very nice tuner that has a reputation for being able to match just about anything.
The workmanship is excellent and it gets great reviews on eHam.
They show up from time to time on eBay, QTH, or eHam. If you can find one it will make a great addition to your shack.