[RockHQ]

A while ago a member of a Finnish bulletin board mentioned having a detailed list of the changes made to 700R4s by GM during the production run. I asked him for it and he was kind enough to provide it, so in turn i'll share it with you. I can not validate the authenticity of the list but i'm positive it's correct.
In addition, 1982-1985 models are not listed but that should not be a big deal since they're pretty much obsolete by now.

1986 New Accumulator Piston, Seal and Spring;
Wider Lo/Reverse Clutch Assembly

1987 Torque Converter Clutch Temperature Switch Added; Orificed
Orifice Cup Plug Added to the Rear of the Case; Electronic
Speed Sensor Added; New Sprag Assembly - Forward Clutch
to Overrun Clutch Hub; New Overrun Clutch Hub; Shift Calibration;
Auxiliary Valve Body Assembly Added; Forward Clutch Checkball
Added, Lo and Reverse Checkball Removed; Double Orifice
Checkball Added to Case; New Spacer Plate; New Spacer Plate
Gaskets; Deeper Oil Pan; Solid Turbine Shaft Oil Ring Seals;
Solid Turbine Shaft Seal Installation; Solid Turbine Shaft Seal
Sizing Tool Alteration; Input Housing Turbine Shaft; Case -
Forward Clutch Feed Passage Eliminated; Oil Pump Cover -
Forward Clutch Feed Hole; Larger Feed Hole Oil Pump Cover;
Reverse Input Clutch Housing; Reverse Input Clutch Piston;
Reverse Input Clutch Packs; Selective Reverse Input Backing Plate;
Lo and Reverse Clutch Piston; Lo and Reverse Clutch Pack;
Selective Lo and Reverse Backing Plate; Input Clutch Housing
and Shaft Assembly; Selection of Forward Clutch Backing Plate;
Forward Clutch Backing Plate; Third and Fourth Clutch Apply
Package; Third and Fourth Selective Plate; Seal Rings on the
2-4 Servo Apply Piston Pin Removed; 2-4 Servo Pin Selection

1988 New Control Valve Assembly; New Input Clutch Assembly
with 3-4 Boost Springs; Reverse Input Clutch Piston;
Case Change - Slot at Lo and Reverse Case Hub; Governor
Driven Gear; Solenoid Assembly and Wiring Harness;
1-2 Accumulator Spring and Valve Body Spacer Plate
YTIVI Model Only

1989 1-2 and 3-4 Accumulator Spring Chart; Control Valve
Assembly; 3-4 Throttle Valve and Sleeve; Spacer Plate;
Piston Seals

1990 Lo and Reverse Clutch Support; 2-4 Band; Forward and
3-4 Clutches

1991 1-2 Accumulator Calibration; 3-4 Clutch Plates (Steel);
3-4 Clutch Plates (Fiber); Output Shaft and Seal; Lo and
Reverse Clutch; 2-4 Servo Cushion Spring and Spacer Plate

1992 TV Limit Line-Up

1993 Garage Shift Package; Solid - Oil Seal (Stator Shaft) (Ring);
1-2 and 3-4 Accumulator; Pressure Regulator Valve; 3-4 Clutch
Pack; 3-4 Clutch Fiber Plate

Thanks go to "capriceman" for providing these details.