Mine is a 1985 740T and it came with a 92 thermostat. I changed it to a 87 since I live in Georgia thinking that it would keep it from getting quite as hot when the air conditioning is on, but it does not make that much difference in really hot weather. The partsbin has the 92 thermostat listed as a cold climate part so I suppose you might get a little more heat in your car during cold weather since it won't open the heat to the radiator until it gets a bit hotter (so you can put more heat into the car). I suppose that 92 would make the pressure a bit higher too but as long as your hoses and cap are in good shape I would not worry about it. Either one should work OK. On mine I noticed that in hot weather on the highway over 75 MPH (with an 87 thermostat) that the engine temp approaches the same range as when it had the 92 thermostat. At least that is what it does on my car.

Randy