Here is the rough lineage of the 4T65-E:
Designed Yr.- Production Yr.- Model

1974 - 1978 - THM-125 (3T40) - Some bushings & bearings carried from
THM-200, some basic designs of splines & shafts from THM-200 and THM-350

1980 - 1983 - THM-440T4 (4T60) - Four speed version of THM-125.  Some parts
identical or very similar.  Somewhat stronger than THM-125.

1983? - 1986? - F-7 - Made exclusively for Cadillac Allante.  Similar
design but many parts different to improve torque capacity.  More
expensive.

1985 - 1988 - 4T60-E - (F-31) Electronic shift version of THM-440T4.  Most
parts identical to THM-440T4.

1991? - 1993? - 4T60-E HD - Same as 4T60-E except with a few heavy duty
parts (mainly final drive gearset) for supercharged 3.8l V-6 application.

1992 - 1997 - 4T65-E - Very similar to 4T60-E with many common components,
but many major differences also.

Below is a synopsis of a previous post with more description of changes
between models:

A little history on the 4T60 used in FWD GM vehicles.
Best viewed fixed font.
      The THM440-T4 was introduced in 1984 on the new GM
full sized luxury vehicles (Oldsmobile Regency 98, Buick
Park Avenue, Cadillac Sedan Deville - remember the logo
on the trunk lid "4-Speed Automatic"). This transmission
was basically the THM125-C with an overdrive added on.
The original 440 was not very reliable.  Many changes
were made the first 3 years.  Areas that suffered many
failures were torque converters (clutch rivets), 2nd
clutch housings, 4th clutch area, final drive.
      When the Cadillac Allante was introduced, the 440
would not handle the torque of the V-8, so a special
version known as the F-7 was developed.  It included
special sprockets, heavy duty final drive, special
fourth clutch, etc.  A rare but solid transmission if
you can find one.
      By 1988 the quality was better, but to make the
440 (now called the 4T60) a world class transmission,
electronic controls were added.  The new transmission was
coded F-31 and became known as the 4T60-E.  The 4T60-E was
phased in from 1988 to 1990.  You can tell by looking at
the bottom oil pan - it will be stamped with "4T60-E".
This transmission has much better reliability.  By the
1991 model year, all FWD Overdrive transmissions were
the 4T60-E model.
      As a side note, with the introduction of the
Northstar V-8s, a new low volume transmission was
developed for these applications.  It is known as the
4T80-E.  Very durable but very expensive, about 80%
higher in cost than the 4T60-E.  Also 60 pounds
heavier.
      With the introduction of the Supercharged 3800,
a few modifications to the 4T60-E were made.  The
biggest change is the final drive unit, which is of
heavy duty design.  The transmission still can't
handle the full torque of engines such as the SC 3800
and the DOHC 3.4L V-6s at redline during shifts. GM
utilizes Engine Torque Management to maintain
reliability.  This consists of controlling engine rpm
and engine torque (through timing and fuel) during
shifts.  That is why the SC 3800 and DOHC 3.4L do
not shift at redline at WOT.
     For the 1997 model year, GM introduce the 4T65-E.
This transmission is a heavily reworked 4T60-E design
which includes such features as a 258mm torque converter
instead of 245mm, twin chains and special sprockets for
noise, Electronic Line Pressure (ELP) for ECM control
of pump pressure to better regulate shift quality,
revised fourth clutch, revised second clutch housing,
and many other improvements to reliability.  The first
applications to receive the 4T65-E will be the
SC 3800 V-6 and the DOHC 3.4L V-6 to minimize the need
for torque management.  The phase in will be three
years and will be complete by model year 1999.
      The biggest cause of failure of the original
4T60 (440) is heat.    [snip of restricted info]   Through
control of shift points and torque converter lockup,
tranmission temperature can be controlled.  There is
a temperature sensor in the transmission for the ECM
to monitor. This shows the STRONG recommendation
to add and external air/oil transmission cooler
for 4T60 (440) equipped vehicles.
      The following is a list of GM FWD transmissions
and their applications:

     Model           Years       Current Application
---------------  ------------  ---------------------
THM125-C (3T40)  1979-2002     J (possibly to 2002)
4T40-E           1995-future   J,N,P-90
THM-440T4 (4T60) 1984-1990     None
4T60-E           1988-1999     All except J,N,P-90
4T65-E           1997-future   SC 3800, DOHC 3.4L
4T80-E           1992-2002     Northstar

Steve Ochs aka N8TYS- Mfg. Engineer - GM Powertrain - Parma Plant
Transmission Division (4T60/65-E) -
The statements and opinions expressed here are NOT an official
statement of General Motors or the GM Powertrain Division