That is interesting but it may just be that the above image may be confused with this US State Department picture from 1983 depicting the modified T-72A tank that got the nickname "Dolly Parton". Not a very clear picture I must admit but I believe I have a rare good quality colour picture of what I believe may just be the real "Dolly Parton". This T72A clearly has the thicker turret armour compared to previous models.
Look at these boobies!
Compared to these kwartz turrets
BTW the late production T-72A did feature a a turret similar to the brand new T72B, but as far as I know very few were built and all were converted to T72B's when they fitted Kontakt-1 ERA.
The tank you are referring to was revealed on 69th Revolution Anniversary parade in 1986.
But it was not T-72B yet. It was referred as "improved T-72A" in Soviet materials.
It is practically impossible to distinguish both, the only clear hint MIGHT be the arrangement of Tucha system.
Obyekt 172M-1 used 902A, while obyekt 184 - 902B with reduced and rearranged positioning of the system awaiting installment of Kontakt-1 package.
As you said, the first is a rare bird suggesting that not many of those have been made, but it is kind of clear thing considering the timetable.
My point is that all the changes in armor package used to be applied on a continuous cycle of natural evolution, for three different tank lines, in three different tank hubs. Some solutions has been used on pair, like monolithic steel casted turrets and kvarz ones, where the kvarz one was slightly thicker.
It is almost impossible to determine some aspects, even now.
For example till now, "quartz" inserts combination is classified.
Everyone in the west tested intensively T-72, that includes US, Germans, Swedes, UK and the French - yet nobody public those data.
Some things cleared only because Poland had a T-72 production line on pair with the Soviets, and produced its own T-72, 72M and 72M1, being respectively obyekt 172, 172M and 172M-1.
Łabędy never mastered new turrets with open cavities and NERA, but they did mastered "kvarz" ones.
Where you can find the data?
Well ... reading the materials provided by the Technical University of Silesia.
They made an article about casting technology revealing that ceramic used is made of quartz sand, aluminum oxide, and titanium dioxide. The binding material was .. clay, and some graphite was added to the mixture, too.
What you get at the end, is a sintered quartz block melted at 1200 deg., looking like this :
Here it is in a cut-open turret, on the right, while on the left it is a monolithic part.
Even the casting technology was covered with some myths, and revealed only because taking out the secrecy stamp in Poland - preformed kvartz blocks were stabilized in the mold using steel bars sticking out of the ready turret main element, and cut after that.
Here you have the markings of it :
And one more interesting thing :
Those are ready for assembling frontal hull plates of PT-91A.
See any steel sheets or glass textolite or STB?
Yeah, me neither