Here is a British technical assessment of the Soviet T-64 tank circa 1978. At this point in time the British and other Western countries had only very limited information on the T-64, so much of this report is based on photographic evidence and the best guesses of intelligence analysts of the period. Therefore, take the info in this report with a grain of salt. That said, it’s an interesting look into what the West knew, or at least thought they new about this revolutionary tank design in 1978.
Summary from report cover page:
This report describes the external features of the Soviet T-64 medium tank derived from photographic intelligence and gives also an assessment of the probable internal arrangements based on intelligence reports matched to the spatial configuration. The appendix to the paper gives details of the turret model used to produce turret sections from which armour distribution of the turret was derived.