This rearend is commonly found in Slant Six and 2bbl V8 Cars, and is only strong enough to get you from Point A to Point B, and not for High-Performance Applications. 

Bolt Pattern: 4" and 4.5"
Years Produced: 1960-1976
Inspection Cover Bolts: 9
Factory Gear Ratio Range: 2.76-3.91
Factory Sure-Grip: Yes
C-Clips: No
U-Bolt Size: 2 7/8"

This rearend is found under most V8 '73-'76 A-Bodies. It is quite strong, and will work great for up to 350hp engines. This rearend is inexpensive, and easy to find, though most have 2.45:1 open gearsets. 

Bolt Pattern: 4.5"
Years Produced: 1973-1976
Inspection Cover Bolts: 10
Factory Gear Ratio Range: 2.45-3.91
Aftermarket Gear Ratio Range: 3.55-4.56
Factory Sure-Grip: Yes
C-Clips: Yes
U-Bolt Size: 3"

The strongest factory rearend offered by Chrysler Corp. in the A-bodies. Can handle about 500hp stock, and is great for quick gear ratio changes. The only downfalls are the rarity, cost, and bolt pattern of this rearend. Mosler Engineering can make you custom 4.5" bolt axles if you desire. 

Bolt Pattern: 4"
Years Produced: 1965-1972
Inspection Cover Bolts: N/A-Drop out Carrier
Factory Gear Ratio Range: 2.76-4.10
Aftermarket Gear Ratio Range: anything
Factory Sure-Grip: Yes
C-Clips: No
U-Bolt Size: 3"

I know what you are thinking...why does he have a Ford Rearend on this page? Simply because a rearend of this type is pretty much a bolt in from a '70's Ford Granada or Mercury Monarch. Hmm...4.5" Bolt pattern, lots of strength, drop-out carrier, etc. Not sounding so bad is it?

Bolt Pattern: 4.5"
Years Produced: 1975-1980
Inspection Cover Bolts: N/A Drop out Carrier
Gear Ratios: 2.79-5.43
Factory Trac-Loc: Yes
C-Clips: No
U-Bolt Size: 2 7/8"