There is an easy way to tell if its an lsd, Jack up the raer of the car and with the car in neutral and handbrake off turn a rear wheel by hand, If they both turn the same direction at the same time it is an LSD or spool. If they spin in opposite directions when one wheel is turned then its an single spinner.
Info courtesy of calaisturbo.com
VL COMMODORE
JATCO 4N71B NA / Turbo
DIFFERENCES
Visually Externally
Small aluminum tag next to Neutral / Start switch Non Turbo X8079
Turbo X8080
Torque Converter Clutch Solenoid located left lower bell housing Non Turbo Yes
Turbo No
Input Shaft O-Ring Non Turbo Yes
Turbo No
Internally
Input Shaft- oil circuit for torque converter clutch with o-ring Non Turbo Yes
Turbo No
Intermediate Shaft- small spigot on end to locate into output shaft Non Turbo No
Turbo Yes
Output Shaft- bushed to accept spigot from intermediate shaft Non Turbo No
Turbo Yes
Pump Housing- contains circuitry and valve for torque
converter clutch Non Turbo Yes
Turbo No
Overdrive Band Apply Piston / Servo Non Turbo 40 x 60mm
Turbo 35 x 60mm
2nd Gear Band Apply Piston / Servo Non Turbo 50 x 72mm
Turbo 52 x 80mm
High / Reverse Clutch - Apply Piston Non Turbo 110 x 52 mm
Turbo 95 x 52 mm
- Number of Frictions Non Turbo 3
Turbo 4
Low Reverse Clutch- Number of Frictions in Turbo transmission greater
due to retaining circlip groove in case being machined higher Non Turbo 7
Turbo 8
Forward Planetary- number of gears Non Turbo 3
Turbo 4
Rear Planetary- both have 3 gears and housings made of Non Turbo Alloy
Turbo Steel
Valve Body- Various differences mainly sizes of valves.
General
JATCO designed several features into the VL Turbo Transmission to cope with the extra torque.
In all areas except one the turbo transmission is bigger or better.
Mechanically the transmission received larger servo / pistons for 2nd and 4th gears, extra frictions in the High / Reverse and Low / Reverse clutch packs, a 4 pinion forward planetary and steel housing rear planetary and added a spigot to the intermediate shaft connecting it to the output shaft. The lock up torque converter circuit is deleted.
The one area they decreased in size was the High / Reverse clutch piston. When shifting from 2nd to 3rd (high) the valve body directs oil to the large area of the 2nd gear piston and the High / Reverse piston. This reduction in area helps control the feel of the 2-3 shift at low throttle settings.
Hydraulically the valve body was modified so that engine boost pressure would help control the transmission line (working) pressure. This enabled good all round shift feel (quality) with the standard engine driven at Volvo-like speeds.
Torque Converter
Factory Code Non Turbo GXA
Turbo NGD
Note. If the torque converter is original (unpainted), all GXA has a
large green paint spot on the top cover
Weight Non Turbo 9 kg
Turbo 8 kg
General
There are three main differences between the GXA and NGD. The NGD had the lock up plate removed, received furnace braising to support the Impellor / Turbine fins and had a slightly different stator giving a higher torque multiplication ratio (stall speed).
