The Ford Ranger came with the Ford 7.5-Inch rear end until 1990 (see note#1) . From 1990 on the Ranger could be found with either the Ford 7.5-Inch or the Ford 8.8-Inch rear axle.
Notes:
1) 1986-up "Incomplete vehicles" also known as "Chassis Cabs" were frequently equipped with 8.8-Inch 28-spline axles, the 1986-1988 examples are distinctive as they are the only 8.8-Inch Ranger rears that have no provisions for a RABS sensor.
2) The 1990 & up 4.0-liter Rangers are ALWAYS equipped with the 8.8-inch 28-spline rear axle.
3) 1998-up 4x4 supercab Rangers regardless of powerplant are frequently equipped with 8.8-Inch axles
4) The FX4 Ranger was introduced in 2002 and always came with 4.10 gears only. The 31-spline Torsen 8.8-inch axle came only with the 2002 FX4 and 2003-up FX4 Level II and more recently was a separate option. The 2003-up FX4 (non-Level II) is essentially the same as the 1998-2002 Off-Road except that a regular Ford limited-slip in a regular 8.8-inch was included.
Swapping in an 8.8-inch 28-spline Ranger axle for the original 7.5-inch axle provides (according to Ford) a 35% increase in strength. But this strength increase refers to the greater strength of the gears and carrier bearings (Pinion bearings, axle bearings and axle shafts are exactly the same) there is NO increase in weight capacity If you are looking for greater strength for loads created by severe offroad driving or towing you'll want to go to the next step, the Explorer axle.
The rear axles on all Ford Explorers are also 8.8's, however there are some differences:
The 8.8-inch Explorer axle use 31-spline axle shaft. Increasing from a 28-spline to a 31-spline axle allegedly increases strength of the axle shaft by 34%, however I'll go by the capacity ratings of the axle assemblies provided by the manufacturer. Ford Rates the Ranger axle at 2750lbs and the Explorer axle at 3200lbs this is a 16% increase in strength, which admittedly may be as conservative as the estimate of axle strength. The Important thing about the Explorer axle assembly (besides its 31-spline shafts) is that its axles are larger in diameter at the outer bearing journal AND the larger diameter bearings used.
It's also important to note that the 1995+ Explorer 8.8-Inch axles come with disk brakes. This is the ultimate stock axle upgrade for your Ranger.
What axle do you have now?
You can identify which axle you have by the tag attached to the inspection cover.
Some feel better having disk brakes (I'll discuss this elsewhere
and if you want discs then look for a 1995-2001 Ford Explorer, as these are the ones with the disk brakes. 1991-1994 axle assemblies are just as strong, but have 10-inch drums (Which are more easily connected to your existing hydraulic lines and Parking brake cables) instead of disks.
Here is an example of an axle tag:
Looking at that tag, you can see the gear ratio stamped on the lower left and the axle size (ring gear diameter) stamped in the bottom middle.
7.5-inch Rear Specifications
7.5-Inch Ring Gear
1.626" Pinion Stem
8.8-inch Rear Specifications
8.8-Inch Ring Gear
1.626" Pinion Stem
Swapping a Ranger 7.5-inch to a Ranger 8.8-inch is a direct replacement. Swapping in a stronger 8.8-inch from an Explorer requires mounting the spring perches from under to over the axle. This should be done by a reputable welder. The 1995 & newer Explorer 8.8-inch axles have disk brakes. The master cylinders in the Rangers are not calibrated for rear disk brakes. When converting to rear disks you should replace your master cylinder with one from a rear disk brake Explorer.
Axle Width Differences:
People have asked about the widths of axle shafts to swap shafts from one axle to another.
The early 1983-1992 Ranger axles are 1-inch shorter than the 1993-up pieces (Both sides). This means that the an entire Ranger axle assembly from 1993-up is 2-inches wider than 1983-1992.
The right side Bronco II axle shaft is 1-5/8" wider than the 1983-1992 Ranger shaft. All of this additional width is on the passenger side. The drivers side shaft is the same length in either axle assembly.
On ALL Ranger/Bronco II's the drivers side axle shaft is longer than the passenger side.
There is no difference between 7.5 & 8.8 axle shaft lengths provided you stay in the same year window.
As a note, if you go to a salvage yard, you may find the left-side shafts removed from 1983-1992 Rangers and Bronco II's. These axle shafts are the same length as the axle shafts in the "Fox" (1979-1993) Mustangs EXCEPT that Ranger/bronco II shafts are five-lug and Mustangs are four lug. Ranger/Bronco II shafts are frequently "pillaged" for use in converting a Mustang to five-lug wheels.
C-Clips:
The 7.5-inch and 8.8-inch axles retain the axles using C-Clips. The C-Clip slides over the end of the axle shaft after it is inserted in to the side gears of the differential. If one of the clips break and falls out of its groove in the axle, the axle will slide out of the axle tube. C-Clip eliminators are available which hold the axle in the axle tube.
Ford Part# SVOM4220A
Moser Engineering 9300
Strange Engineering A1092
Axle Girdle:
Serious Off-Roaders may consider installing an Axle Girdle. They Replace the existing inspection cover and provide support to the differential bearing caps. They also increase the fluid capacity.
Ford Part# M-4033-G (8.8-inch)
Ford Part# M-4033-J (7.5-inch)
Jegs Part# 6-9-101-8.8 (8.8-inch)
Heavy Duty Differential Covers:
A heavy duty differential cover is a must for the serious offroader. The stock stamped cover can bend and even get torn off if it catches on a rock or other solid trail obstacle. It can also get smashed in against the ring gear. Many companies now offer heavy duty covers like the one below from Solid Axle.
Axle Codes:
Rear axle codes can be found on the Safety Standard Certification label attached to the left drivers side door lock post. The code appears as a number or letter/number combination in the 'Axle' column of the label. The axle can also be identified by the tag on the axle differential cover bolt. See the diagram above to learn how to read the tag.
Axle codes for Ranger, Bronco II, Explorer and Aerostar (included because 4.10 gears and limited slips are more common than you'd expect)
----------
3.55
(Note: Aerostars with axle codes starting with "1" are Spicer/Dana 30 axles with Aluminum housings)
2950
4.10
23
open 7.5"
2950
3.45
24
open 7.5"
2950
3.73
25
open 8.8"
2950
3.27
29
open 8.8"
2950
3.55
B2
L/S 7.5"
2950
4.10
B4
Bronco II
Code
Description
Capacity
Ratio
42
open 7.5"
2640
3.45
44
open 7.5"
2640
3.73
47
open 7.5"
2640
4.10
D2
L/S 7.5"
2640
3.45
D4
L/S 7.5"
2640
3.73
D7
L/S 7.5"
2640
4.10
Ranger
Code
Description
Capacity
Ratio
72
open 6-7/8"
2200
3.08
74
open 6-7/8"
2200
3.45
82
open 7.5"
2750
3.08
84
open 7.5"
2750
3.45
86
open 7.5"
2750
3.73
87
open 7.5"
2750
4.10
91
open 8.8"
2750
3.27
92
open 8.8"
2750
3.08
95
open 8.8"
2750
3.55
96
open 8.8"
2750
3.73
97
open 8.8"
2750
4.10
98
open 8.8"
2750
4.56
F4
L/S 7.5"
2750
3.45
F6
L/S 7.5"
2750
3.73
F7
L/S 7.5"
2750
4.10
R5
L/S 8.8"
2750
3.55
R6
L/S 8.8"
2750
3.73
R7
L/S 8.8"
2750
4.10
R8
L/S 8.8"
2750
4.56
(Note 4.56 geared axles '99-up are 31-spline)
Explorer
Code
Description
Capacity
Ratio
41
Open 8.8"
3200
3.27
43
Open 8.8"
3200
3.08
44
Open 8.8"
3200
3.73
45
Open 8.8"
3200
3.55
D1
L/S 8.8"
3200
3.27
D2
L/S 8.8"
3200
4.10
D4
L/S 8.8"
3200
3.73
D5
L/S 8.8"
3200
3.73
L - Limited Slip Differential
C - Conventional Differential
Code
Ratio
85
3.55C
89 (1992-1998)
4.10C
89 (1999-2001)
4.56C
F5
3.55L
K6
4.10L
Lockers: