There is apparently more than one "Magnum Dynalab". I remember reading about that.... somewhere/when.
This is from Magnum Dynalab's website:
"With the introduction of a simple, yet revolutionary product over 20 years ago, Magnum Dynalab's legacy began. Our incredible Signal Sleuth, designed to boost and stabilize FM signals, was launched in
1984 and eventually led to the introduction of what would become our core product line for many years; world-leading analog FM tuners for the home market."
http://www.magnumdynalab.com/history.htm
That receiver is older than that.
More digging is indicated.
edit: The name Dynalab (as well as Dyna Lab) is used by several companies. At one time, some early Dynaco products were called Dynalabs, but the above item is not one of them. There is a Canadian company that is an OEM electronics manufacturer that uses the name Dynalab, but their website says they got started in 1981, and I think that is too late for that receiver. An SQ receiver would likely have been built around the mid 70s. I will point out that the AC receptacles on the rear of that unit are not polarized, which also tends to date it to the (so-called) vintage era.
A few years back I was looking long and hard at buying a Magnum Dynalab tuner, and that was when I ran across a notation about there being more than one Dynalab out there, but for the life of me I can't remember if it was on Audio Asylum, Audigon, fmtunerinfo.com...... I am old, and have a terrific case of CRS.
Hopefully the folks at the present day Magnum Dynalab will be able to point you in the right direction.