here's what CIA thinks of FCSes in the early 80s. I should probably go sleep.
This is an interesting document, which may be relevant to our interests.
Apparently, some AMX-30Bs were fitted with battlefield radars. Exceptional optics recon tank, anyone?
Merkava Mk. 1 fire control systems were some sort of bizarre mix between a Leopard 1A4 and an M60A3- so that's a nerf.
Early Type 74 fire control systems were apparently similar to an M60A3's but it was missing some of the environmental sensors...
Estimates on east bloc systems are as unreliable as you'd expect.
Strv 103B has no FCS at all, or a rangefinder- just a big scope. Not much of a surprise considering it's from the mid '60s.
M47 has a stereoscopic rangefinder and a (very, very primitive) ballistic computer, which was amazingly still being made in Italy at that late date.
M48A2+ has a coincidence rangefinder and a slightly less primitive ballistic computer.
M60A1/AOS/RISE have more or less the same computer and are basically product-improved M48s as far as fire control goes.
M60A2 has a full FCS- first actual one in the US.
M60A3 is the vanilla of fire control systems- laser rangefinder, environmental sensors, etc.
The M1 is like above, except slightly better at calculating lead.
Leopard 1-A4 are like the M60 in fire control operation.
Leopard 1A4 is a hybrid system- fancier than the ones that came before it, M60s, etc, but not as fancy as M60A3, T-64B, etc.
Export Leopard 1s fitted with the SABCA system (that's our ANZAC and Canadian Leopards) are similar to the M60A3 in terms of FCS. That is to say, better than the 1A4. Dutch, Danish, and Norwegian pre-A5 leopards DO NOT have this.
Everything else is not much of a surprise or already well-known.