GM 8-1/2-Inch 10-Bolt
With its round cover design, the 8-1/2-inch 10-bolt is a semifloating, integral design. Its claim to fame is that it replaced the Dana 44 in '77 when GM decided to use its own products.
Applications: '77-'87 C10/K10/K20, '80-'94 Blazer, '80-'94 C10/K10, '88-'00 K1500/K2500
Ring-gear diameter: 8.5 in
Pinion-gear diameter/splines: 1.626/28 and 30 splines
Available gearsets: 2.73, 3.08, 3.23, 3.42, 3.70, 3.73, 3.90, 4.10, 4.11, 4.56, 4.88, 5.13, 5.38, and 5.57

Toyota 8-Inch
Also referred to as a 7.8-inch (Americans rounded up the figure), two versions of the 8-inch appeared in Toyotas over the years: one for four-cylinder applications and another for the turbo four-cylinder and V-6 models. The only difference between the two is that the four-cylinder model uses shorter pinion gears. Both units are dropouts and are recognizable by the nonremovable, humped rear cover and breather tube on the top of the housing.
Applications: '79-'85 Toyota (four-cylinder model), '86-'96 Toyota, '86-'96 Toyota (turbo/V-6 model)
Ring-gear diameter: 7.8 in
Pinion-gear diameter/splines: 1.378 in/27 splines
Available gearsets: 3.70, 3.90, 4.11, 4.37, 4.56, 4.88, 5.29, and 5.71

Dana 44
The Dana 44 went into production in the late '40s and has since appeared in virtually every make of production four-wheel-drive vehicle. On the street side, the 44 found its way into some Chevys and Fords. It has a 10-bolt cover design and was produced with 30-spline axleshafts.
Applications: '60-'70 C10/15, '67-'78 F-100/F-150 4x4
Ring-gear diameter: 8.5 in
Pinion-gear diameter/splines: 1.376/30 splines
Available gearsets: 2.72, 2.87, 3.07, 3.23, 3.31, 3.54, 3.73, 3.92, 4.09, 4.27, 4.56, 4.89, 5.38, and 5.89

Dana 60 (also 50)
Looking like a larger version of the Dana 44, the Dana 60 can be identified by its 12-bolt pattern. The housing is made from nodular iron, which provides excellent rigidity and strength over other housings. Still in production today, the Dana 60 is offered in both semi- and full-floating configurations and is touted as one of the strongest and most reliable units available.
Applications: '67-'85 F-100, '67-'85 F-150, '67-'92 F-250, '78-'92 F-350, numerous Chevrolet, Dodge 3/4- and 1-ton
Ring-gear diameter: 9.75 in
Pinion-gear diameter/splines: 1.626 in/30 and 35 splines
Available gearsets: 3.33, 3.54, 3.73, 4.10, 4.56, 4.88, 5.13, 5.38, 5.57, 5.86, 6.17, and 7.17

The Final Word
Armed with this info, you should be able to know your rearends and what they fit and what gears you can get. The lug pattern sidebar should help you determine if you can stuff those sweet Escalade wheels your buddy has on your Nissan pickup.