Axle, Positraction limited slip

required with 4.10/4.56/4.88 (67-68), 3.73/4.10 (69)

$43.05 for 1963

15,911 MC in 1970

All light trucks (1963 GVW selector shows G81 — likely OCR/early variant)

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the kit pages print locking differential (G8O on some pages); Positraction is the merged second-generation doc's reading from GM lists.

2004 and 2005 lists read "Axle Positraction Limited Slip". The 1995 to 1997 guides print locking differential.

the kits print it as the locking differential; the 1993 technical guide prints G8O

the kits print it as the locking differential; the GMT400 doc reads it from GM lists as Positraction; the 1983–1986 price pages print G8O; the 1991 option page prints GaO, so 1991 is left out

requires an optional axle ratio; the kit pages also print G8O; the 1988 option page prints G3O, so 1988 is left out; the merged second-generation doc reads it from GM lists as Positraction, limited slip; the 1989-labelled kit runs the code into the name (G80Locking), so 1989 stays on the 1990 file page

1998 and 1999 lists read Positraction only

1990 from the axle identification page, which heads the limited slip identification as the G80 option, with the 1990 order guide naming the limited slip axle; 1991 and 1992 are not claimed: the weight pages list it, but the option pages name the limited slip axle only inside the Z28 base equipment group contents

2001–2002 lists add "limited slip"

GM Authority 2014 RPO list

not with G92 (1988) or F41 (1990)

1991: with a performance ratio (3.08 sedan, 3.23 wagon), not with F41; 1995: requires L99, includes the 3.23 axle

the kit pages also print G8O

the kits print it as the locking differential; the GMT400 doc reads it from GM lists as Positraction; the kit pages also print G8O

2015: Z71: S; WT, LT: O; Base: not offered; the upfitter lists name it a positraction limited slip axle; 2018 from GM's 2018 Colorado order guide (PDF); 2021 from the upfitter list GM files for 2021 and 2022

Trail Boss, Z71: S; WT, LT: O; ZR2: not offered

The 1984 order guide prints G8O (letter O)

the 1998–2000 lists read "Rear Axle, Positraction"; the 2001–2002 lists print G8O, a letter O, for the same wording as GM's other lists give G80; the 1996–1997 order guides read Locking Differential

the 2025–2027 guides read Differential, heavy-duty locking rear; O: Cargo 1WT, Cutaway 1WT, Cutaway 2WT (2025–2026), Passenger 1LS, Passenger 1LT

the 1983, 1984, 1986 and 1995 pages print G8O; 1984 from the 1984 data book pages in the kit file labelled 1985.

standard with the 3.08 axle (1994 standard equipment summary)

sedan and wagon

the 1986–1987, 1989–1990 pages print G8O

1998 and 1999 lists read Positraction only. The 2002–2004 lists read as the 2001 list.

the 2001–2007 lists word it as a Positraction limited-slip axle

the 2001–2007 service lists word it as a Positraction limited-slip axle; the 2003 and 2005 order guides word it as a heavy-duty locking rear differential, as the 1999–2000 lists and the Silverado GMT800 doc do

the 2014 guide words it as a heavy-duty automatic locking rear differential

2017: GM's 2017 Silverado 2500HD order guide; 2018: GM's 2018 Silverado 2500HD order guide; 2019: GM's 2019 Silverado 2500HD order guide

2023 is not claimed: the 2023 Upfitter list reads G80 as the Positraction limited-slip axle, a different part

the 2017 manual reads limited slip.

the Silverado HD (T1XX) doc reads G80 "Differential, rear, auto-locking" from the pickup lists

the 2020 list reads "Differential, heavy-duty locking rear"; the 2025–2026 lists read "Auto-locking rear differential";

S

the 2005 kit guide splits it by gearbox (Zexel-torsen with the automatic, Eaton with the manual), shown without the code on pages 90 and 99

The 1992–1997 order guides print locking differential

the 2000 list words it as a locking rear axle

The 2014 guide words it as differential, heavy-duty locking rear.

2016: S on all trims; the lists read limited slip; 2018–2019 from GM's 2018 and 2019 Suburban order guides (GM Authority copies)

the GMT400 doc reads it from GM lists as Positraction; the 1983–1988 option pages print G8O (1988 from the January 1988 price page)

The kits print it as the locking differential; the 1996–1997 kit page prints G8O

the 2000 list words it as a locking rear axle

The 2014 guides word it as differential, heavy-duty locking rear. Trim marks in the 2014 guides: Police: O; Special Service: O.

2016: S on all trims; the lists read limited slip; 2018–2019 from GM's 2018 and 2019 Tahoe order guides (GM Authority copies)