The T86 is a top loaded, top shifting, three-speed transmission. The T86 is fully synchronized in the second and third gears.
The T86 transmission is 9" long and features a cast iron top cover that is retained by six bolts and a main case of cast iron.
With the advent of the Buick V6, the T86 three-speed transmission was first installed in the Jeep CJ in 1966. It was retained through mid-1967, at which point it was replaced by the T14 transmission.
The T86 is very similar in appearance and build to the Jeep T90, and these gearboxes can be confused with each other on first glance. The T86 will typically be cast with "T86AA" on its case. Also, upon internal inspection, one can confirm it as a T86 in that all gears are helically cut, including the first mainshaft gear.
All T86 transmissions have a 1-3/8" x 6 spline output shaft for mounting the transfer case input gear. The T86 featured a 4" diameter rear bearing retainer as the centering locator. The Jeep T86 was factory-married to the Jeep Dana Spicer Model 18 transfer case, and only the large input bore versions.
The T86 was factory married to the Buick V6. Because of its strength, it is not often adapted to upgrade engines.
The T86 and AMC eras are anachronistic and the transmission was never joined to an AMC engine. There are neither factory nor aftermarket provisions nor compelling reasons to do so.
The T86 is straightforward to rebuild, not too dissimilar to a T90 rebuild.
The T86 was put forth as a transmission capable of handling the greater torque as offered by the rowdy Buick V6. The gig was up after only two years of customer's field use, as the actual durability of the transmission fell short of the advertised strength. However, for normal to moderate usage, the T86 is usually adequate.