'Big Diff' refers to B0xx-series 220mm ring gear size differential

'Small Diff' refers to A0xx-series 200mm ring gear differential

'Big flange/Small flange' refers to the 3- bolt input flange (aka companion flange) that bolts to the driveshaft. This flange can be changed out on both 200mm and 220mm differentials

Picture: left B-series 220mm "big diff" right A-series 200mm "small diff"

US Spec:

YEAR	CODE	GEAR	LSD/OPEN
1993-1996	A05A	4.272	OPEN
1993-1996	A05B	4.272	LSD
1997-1998	A02A	3.769	OPEN
1993-1996	A02D	3.769	LSD
1993-1998	B07D	3.133	LSD
1997-1998	A01A	4.083	OPEN
1997-1998	A01B	4.083	LSD

JDM: 

MODEL	CODE	GEAR	LSD/OPEN
SZ (auto/5spd)	A01A	4.083	OPEN
SZ (auto/5spd)	A01B	4.083	LSD
SZ-R 6speed	A02A	3.769	OPEN
SZ-R 6speed	A02B	3.769	LSD
RZ Auto / GZ  (auto/5spd)	A02A	3.769	OPEN
RZ Auto / GZ  (auto/5spd)	A02B	3.769	LSD
RZ 6speed (93.5-96 V160)	B03B	3.266	LSD
RZ / RZ-S 6speed (96.5-02 V161)	A03B	3.266	LSD

EURO / GCC (arab) / GEN (general):

YEAR	CODE	GEAR	LSD/OPEN
1993-1996 Auto EU Spec	B04D	3.538	LSD
1993-1996 Austria/Switz Spec	B03D	3.266	LSD
1993-1996 EU 6speed	B03D	3.266	LSD
1993-1996 GCC NA 5spd	B04A	3.538	OPEN
1993-1996 GCC NA 5spd	B04B	3.538	LSD
1993-1996 GCC NA Auto	N/A	3.769	N/A
1993-1996 GEN Na 5spd	N/A	4.083	N/A

 

US spec vehicles:

92-00 Lexus SC300 auto---- 4.272:1, open, small diff, small flange

92-97 Lexus SC300 5spd---- 4.083:1, open, small diff, small flange

92-96 Lexus SC400 (auto)---- 3.916:1, open* small diff, small flange

1997 Lexus SC400 (auto) after MC but before going to 5AT trans - 3.916:1, open, small diff, BIG flange. 

98-00 Lexus SC400 (5AT trans, VVTi)---- 3.266:1, open, small diff, big flange

93-95 Lexus GS300 (auto)---- 4.083:1, open, small diff, small flange

96-97 Lexus GS300 (auto)---- 4.272:1, open, small diff, small flange

98-00 Lexus GS300 (auto)---- 3.916:1, open, small diff, small flange (US Market)

98-00 Lexus GS300 (auto)---- 3.615:1, open, small diff, small flange (UK/Europe Market)**

98-00 Lexus GS400 (5AT auto)---- 3.266:1, open, small diff, big flange

02-05 Lexus SC430 (auto)---- 3.266:1, open, small diff, big flange***

06-10 Lexus SC430 (auto)---- 3.769:1, open, small diff, big flange***

I need verification on more of the 00-up Lexus models, anyone with a source of this info PLEASE let me know! 

JDM vehicles: 

91-97 Aristo 3.0V (2JZ-GTE model, auto)---- 3.769:1, LSD optional, small diff, big flange

91-00 Soarer 2.5GT-T (Auto and 5spd?)----- 4.083:1, LSD optional, small diff, small flange

91-97 Soarer 4.0GT (auto) ----- 3.916:1, LSD optional but rare, small diff, big flange

 

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Source: http://www.supraforums.com/forum/showthread.php?608545-JZA80-Differential-Info!