4 Wheel Drive/SUVs: 4/4 gmc 3//4 ton chevy truck

Question
did 1986 3/4 ton gmc 4x4 trucks come with posi track or limited slip rear ends

Answer
Gary,

As far as I know, the Eaton Automatic Differential Lock came as an option.

A new Eaton Automatic Differential Lock (ADL) was introduced in 1973 as an optional extra on the Rounded-Line C/K-Series pickups, for the rear hypoid differential. The new automatic locking differential was offered under the G86 code, replacing the Eaton NoSpin differential, and eventually replacing the old Positraction limited-slip differential in 1974, at which point it assumed the G80 code.[39] The Eaton ADL featured intelligent differential control via an internal governor which monitored vehicle speed and wheel slip to know when to automatically lock and could lockup 100 percent at or below 20 mph (32 kph) increasing tractive effort. The differential lock would unlock and deactivate at speeds above 20 mph for safety reasons, such as the vehicle being on dry pavement.[4

Here is an address for the service manual fo4 73-87 chevy trucks.
http://www.73-87chevytrucks.com/techinfo/7387CKMans//Service/X8632_1986_GMC_Ligh

Carl