Who can give us all the scoop on rear diffs??

[presleyhome]

What are the differences in the rear-ends? Full floater, partial float, open vs closed, locker vs posi, etc. I believe my 81 has a 14 bolt 10.5".

What would be the preferred one for c10, c20, k10,3k20 etc.

Seems there is much magic to know about these.....

Thanks,

Jim P

[cdowns]

factory service manual is chok full of usefull info

[LONGHAIR]

There is a lot to deal with here.

But the "basics" are this...
The main difference between "Full Floating" and "Semi Floating" is simply in the way the wheel is attached. With a "semi floating" rear end, the wheel is bolted directly to the axle. The axle holds the weight of the car/truck.
A "full floating" rear end is very similar to a front axle of a 4 wheel drive, except that it doe no turn of course. The wheel is bolted to the hub/drum that is mounted to a "spindle"....the axle slides through the middle. The axle is not holding the weight, just providing the drive.

As far as "differentials"....
"Open" is the opposite of some kind of "traction device". "Open" is just a simple spider geared differential (Spins one wheel)
There are several different types of "Traction devices". The all are trying to accomplish the essentially the same thing, power to both wheels, while still allowing some slipping to allow turns on city streets with out tire squeeling/bucking/jerking etc. Some are more "harsh" than others, but they generally provide better traction too, so it's somewhat of a trade-off.
"Clutch-type" units are probably the most common, these are what most people refer to as "Posi-traction". They work well and are faily forgiving, probably the best "all around" choice.
Detroit Lockers are much harsher to live with are are generally not recommended for the average daily driver....a lot of guys do it, myself included, it was even a factory available option back in the day.