I've got a 1991 camry with the 3S-FE 4 cyl DOHC engine and manual transmission. I just purchased the car and it needs a transmission fluid change. I purchased the Haynes manual for it, and it recommends dextron 3 ATF for 4 cylinder models equipped with a manual transmission, but 75W-90 gear lube for V6 models equipped with a manual transmission. Something doesn't seem right to be about that. I would think the two transmissions would be the same internally, so why the different recommendation? Should I use the atf of go with the 75w-90 gear lube?

Use gear lube

From the AMSOIL website:
http://www.amsoil.com/scripts/runisa.dll?amsoiloaf:index

1991 TOYOTA CAMRY 2.0L 4-cyl VIN Code G 3S-FE

FILTERS
Oil Filter......SDF10
Oil Vapor Filter......N/R
Air Filter......TS76
Fuel Filter......GF288
Fuel Vapor Filter......N/R
PCV Valve......N/R
Trans......TF117

BOSCH SPARK PLUGS
LE ALL TRAC
Wire......B09980[1]
Plug......B4418[1]
LE
Wire......B09980[1]
Plug......B4418[1]
DLX ALL TRAC
Wire......B09980[1]
Plug......B4418[1]
DLX
Wire......B09980[1]
Plug......B4418[1]
ALL TRAC
Wire......B09980[1]
Plug......B4418[1]
All other Submodels
Wire......B09980[1]
Plug......B4418[1]

1. Cap/Wire design set
Cap/Wire design set

BOSCH WIPER BLADES
Driver side......B40919
Passenger side......B40917
Rear window......B40915

CHASSIS LUBRICATION
0 Fittings, 0 Plugs

LUBRICANTS & FLUIDS
Engine Oil
Grade 1......API*
Synthetic 5W-40 European Engine Oil
SAE 10W-40 Synthetic High Performance Motor Oil
SAE 10W-40 XL-7500 Synthetic Motor Oil
Above 0°F......10W-40
Manual Transmission,4WD.....GL-4
Above -18°C......90 Gear Oil, API Service GL-4
Manual Transmission,4WD.....GL-5
All temps......75W-90, 80W-90
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
Manual Transmission,4WD.....GL-5
Above -18°C......90 Gear Oil, API Service GL-5
Manual Transmission,4WD.....GL-4
Below -18°C......80W Gear Oil, API Service GL-4
Manual Transmission,2WD from 4/90.....GL-5
All temps......75W-90
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
Manual Transmission,2WD from 4/90.....GL-4
All temps......75W-90 Gear Oil, API Service GL-4
Manual Transmission,4WD.....GL-4
All temps......75W-90, 80W-90
SAE 80W-90 Synthetic Gear Lube
SAE 80W-90 Synthetic Lower Unit Gear Lube
Manual Transmission,4WD.....GL-5
Below -18°C......80W
Gear Oil, API Service GL-5
Automatic Transmission,4WD.....TTA[1]
Synthetic Automatic Transmission Fluid
Automatic Transmission.....AF3
Synthetic Automatic Transmission Fluid
Torque-Drive™ Synthetic Automatic Transmission Fluid (ATD)
Differential, Front .....AF3[2]
Synthetic Automatic Transmission Fluid
Torque-Drive™ Synthetic Automatic Transmission Fluid (ATD)
Differential, Rear .....GL-5
Above -18°C......90
SAE 80W-90 Synthetic Gear Lube
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
Transfer Case,.....GL-5[3]
Below -18°C......80W
SAE 80W-90 Synthetic Gear Lube
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
[3]
Above -18°C......90
SAE 80W-90 Synthetic Gear Lube
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
[3]
75W-90, 80W-90
Severe Gear 75W-90
SAE 75W-90 Synthetic Gear Lube
SAE 80W-90 Synthetic Gear Lube
Fluids
Power Steering Fluid.....AF3
Synthetic Automatic Transmission Fluid
Torque-Drive™ Synthetic Automatic Transmission Fluid (ATD)
Brake Fluid.....HB
Hydraulic Brake Fluid, DOT-3
Clutch Fluid.....HB
Hydraulic Brake Fluid, DOT-3

1. TTA is Type T ATF, Toyota part no. 08886-00405
2. Final drive for automatic transmission only.
3. Trc W/ automatic transmission only.

CAPACITIES
Engine, without filter..........3.9 quarts[1]
Cooling System, Initial Fill..........6.9 quarts
Automatic Transmission, 2WD Initial Fill..........2.5 quarts[2]
Automatic Transmission, 4WD Initial Fill..........3.5 quarts[2]
Automatic Transmission, Total Fill
4wd ..........7.4 quarts
fwd ..........6.3 quarts
Manual Transmission, 2WD..........5.5 pints[3]
Manual Transmission, 4WD..........11.0 pints[4]
Differential, Front..........3.4 pints[5]
Differential, Rear..........2.3 pints[6]
Transfer Case,..........1.5 pints

1. Capacity shown does not include filter. When replacing
filter additional oil may be needed. After refill check oil
level.
2. With ENG automatic transmission operating temperature, shift through all gears. Check fluid level in PARK and add fluid as needed.
3. Capacity includes final drive.
4. Capacity includes transfer case.
5. Final drive for automatic transmission only.
6. Rear diff is for 4wd models only.

TORQUES
Oil Drain Plug.....29 ft-lbs
Oil Drain Plug.....18 ft-lbs
Manual Transmission
Fill Plug.....36 ft-lbs
Drain Plug.....36 ft-lbs

CAUTIONS
TRANS/DIFF
4WD W/ MT: To drain front differential,
transfer case and transmission, remove two
drain plugs. One is located on the bottom
of the case between the front axles, the
other is located under the drivers side
axle on the side of the case.
TRANS/DIFF
4WD W/ AT: Transmission and front final
drive share the same lubricant and drain/
fill together. Transfer case is a separate
component. Drain transfer case through
drain plug on case, fill through dipstick/
filler tube.

SERVICE INTERVAL
http://www.amsoil.com/lit/g1490.pdf

Wow, what a great answer BrianR! Everybody should print that out and tape it to the hood!

Thank the guys who run the AMSOIL website.

I've got a 1991 camry with the 3S-FE 4 cyl DOHC engine and manual transmission. I just purchased the car and it needs a transmission fluid change. I purchased the Haynes manual for it, and it recommends dextron 3 ATF for 4 cylinder models equipped with a manual transmission, but 75W-90 gear lube for V6 models equipped with a manual transmission. Something doesn't seem right to be about that. I would think the two transmissions would be the same internally, so why the different recommendation? Should I use the atf of go with the 75w-90 gear lube?
Wait! Amsoil does not make a manual transmission oil, its a differential lube. dont use in tranny. please check your info. BTW redline makes a good tranny lube.

Wait! Amsoil does not make a manual transmission oil, its a differential lube. dont use in tranny. please check your info. BTW redline makes a good tranny lube.

Read the AMSOIL information about the recommended gear oils before you make that statement.

Here's a quote from AMSOIL:
http://www.amsoil.com/storefront/fgr.aspx
Long Life 75W-90 Gear Lube
Applications
AMSOIL Long Life Synthetic Gear Lubes, in the correct viscosity grades, are recommended for all domestic and foreign applications such as over-the-road trucks, light, medium and heavyduty trucks, off-road equipment, commercial vehicles, motorhomes, autos, SUVs, emergency vehicles, busses, delivery/utility vehicles and tractors.

Use AMSOIL Extended Drain Synthetic Gear oils in differentials, manual transmissions or other gear applications where one or more of the following standards are specified: API GL-5 & MT-1, MIL-PRF-2105E, Dana SHAES 234 (Formerly Eaton PS-037) for 250,000 miles, Dana SHAES 256 (Formerly Eaton PS-163) for 500,000 miles, Mack GO-J & GO-J+, Meritor 0-76N, and Navistar TMS 6816 plus hypoid gear oil specifications from all foreign and domestic manufacturers such as GM, Ford and Daimler Chrysler. Can also be used in rear axles where API Service GL-4 lubricant is recommended.

Another recommended oil is:
http://www.amsoil.com/storefront/svg.aspx
with a similar recommendation.

To me, that means they say they are appropriate for use in transmissions. So, unless they buy it and repackage it, they make it.