The 4L80E made a slight change with some stronger parts, does
anyone know what year that was and what GM changed. Mine
is a 1995 I hope I have a good one.
Thanks
Loy

1996 up is usually a better unit. Some folks like 1998 up. GM has updated some internals here and there.

the biggest changes were in the oiling circuits

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Save the earth , choke a tree .... save a squirrel

Well I guess I got shafted on this one, I didn't know until today
they had a date on the side.

I copied and pasted the below info from another forum where we were discussing the 4L80E. Notice the MN8 is the heavier duty 80E unit and also from my understanding that particular unit can be found in motor home chassis as well as the listed truck applications. Also, Im not sure which gear set it is but the MN8 has less helically(sp?) cut gearing which makes for a stronger but slightly noisier unit. If youve ever heard the sound an M22 "rockcrusher" muncie 4spd makes you'll know what Im speaking about.

Anyways here ya go:

Hydra-Matic 4L80-E/4L85-E Transmission (MT1/MN8)

Type: four speed rear-wheel-drive, electronically controlled, automatic overdrive transmission with torque converter clutch
Engine range: 4.8L - 8.1L gasoline
6.5L diesel
Maximum engine torque: 440 lb-ft (597 Nm) (MT1)
460 lb-ft (624 Nm) (MN8)
Maximum gearbox torque: 885 lb-ft (1200 Nm)
Gear ratios:
First: 2.48
Second: 1.48
Third: 1.00
Fourth: 0.75
Reverse: 2.07
Maximum shift speed: 1-2 5200 rpm
2-3 5200 rpm
3-4 5200 rpm
Maximum validated gross vehicle weight: up to 16,500 lb (7483 kg) (application & axle ratio dependent)
7-position quadrant: P, R, N, OD, D, 2, 1
Case material: die cast aluminum
Shift pattern: (2) two-way on/off solenoids
Shift quality: force motor control
Torque converter clutch: pulse width modulated solenoid control
Converter size: 310mm (reference) (diameter of torque converter turbine)
Fluid type: DEXRON III
Transmission weight: wet: 115 kg (254 lb) (MT1)
wet: 115.5 kg (255 lb) (MN8)
Fluid capacity (approximate): bottom pan removal: 4L - 6L (4.2 qt - 6.3 qt)
Pressure taps available: line pressure
Towing capacity: up to 21,000 lb (9525 kg) maximum gross combined vehicle weight (application & axle ratio dependent)
Assembly sites: Ypsilanti, Mich.

Applications: Chevrolet Avalanche (MN8)
Chevrolet Silverado and GMC Sierra 2500HD & 3500 series
Chevrolet Suburban and GMC Yukon XL (MT1/MN8)
Chevrolet Express and GMC Savana (MT1)