Front differential problem

Without additional information about the specific model and trim of your 2005 turbo diesel 4x4 Courier, it's difficult to say exactly which rear differential centers would fit your vehicle. However, I can offer some general guidance to help you with your search.
The best way to ensure that you get the correct rear differential center for your vehicle is to consult the vehicle's owner's manual or contact a dealer or mechanic who specializes in your make and model of vehicle. They will be able to provide you with information on the exact specifications of the differential and any compatible replacements.
That said, some possible options to consider include rear differential centers from other Ford vehicles that share the same platform or drivetrain as your Courier. For example, the Mazda B-series pickup truck, which was sold in some markets as a Ford Ranger, may share some common components with the Courier. The Ford Explorer and Ford Bronco II are also possibilities, depending on the specifics of your Courier's drivetrain.
It's important to note, however, that even if a differential center from another vehicle fits your Courier, there may still be differences in gear ratios, splines, and other factors that could affect its compatibility and performance. For this reason, it's generally recommended to use a direct replacement part whenever possible.
In any case, I would strongly recommend consulting with a qualified mechanic or parts specialist before making any purchases to ensure that you get the correct part for your vehicle.

Start with the basics first.
Check that main transmission is not in neutral and that the centre transfer box is also not in neutral.
Check the mounts where the prop shaft connects to the rear differential to make sure the two are connected.
Has there been a previous problem with the transmission, propshafts or differentials that could have caused this problem?
Chock the front wheels, raise both side of the rear of the car and rest them on axle stands. Put the vehicle into neutral with the hand brake OFF. Hand turn one rear wheel and watch the other. They both should turn.
Get under the vehicle and hand turn the propshaft. This might take some effort. With the wheels off the ground the wheels should turn. If not, you have a problem with the differential that needs a specialist to fix it.

IF you are in constant 4wd then you will not have a centre diff unless you have an AWD. The difference is that AWD transfer cases have a centre diff that allows different road speeds between the front and rear diffs as in going over speed bumps and dips ion the road It is the same operation in the front and rear diffs that allow one wheel to go faster than the other when cornering. However in 4wd drive there is no diff action in the transfer case and both front and rear axles drive at the same speed regardless of speed bumps and dips in the road . This action produces what is known as torque wind up which results in the handling characteristics. This torque wind up places stress on all the drive line train and results in failures such as .that you describe.. This wind up is not noticeable when driving on loose surfaces slippery surfaces or in mud as it is allowed to escape when the wheels spin . If you have an AWD with diff lock capabilities then check that the diff lock is operating correctly

AWD vehicles have a centre diff in the transfer case and if there is no traction on the rear wheels then the front wheels will not turn. All wheel drive is not equal to 4 wd which you assume apparently. Check that there is not a diff lock button in the car to lock the centre diff turning it into 4wd vehicle in which case the front wheels would have moved the vehicle

all wheel drive vehicles have to work at both ends all the time unless you have a major failure in the drive train. That is why it is called all wheel drive as opposed to 4 wheel drive. With 4 wheel drive you have the option of rear wheel drive or 4 wheel drive and normally in a high ratio or low ratio gear selection. With some all wheel drive vehicles there is a selector that locks the middle diff and creates a 4 wheel drive option without the high/low gear ratio option. So in practice if the both front wheels are in the bog then there is no all wheel drive as the centre diff is working as it should and placing all the action in the rear wheels which will not be turning as they have traction so the front wheels spin faster.. If you have a centre diff lock option ensure that it is operational.

To remove any diff you have to remove the axles as they will hold the diff centre in the housing. Remove drive shaft and the bolts around the diff centre. you may need to break the gasket seal to get the centre to move. A workshop manual for the vehicle would be the best idea you would have.

Does it have manual locking front hubs? Some people fit these to full time four wheel drive vehicles to reduce driveline effort and increase fuel efficiency. The issue is that the drive from the transfer case will find the path of least resistance which if the front hubs are not locked power will be sent through the front diff and only spin the front drive shafts. To ensure drive power is sent to the rear diff the centre diff needs to be locked. If you do have manual locking front hubs try putting them in the locked position and leave the centre diff button off and try going for a drive.

diff lock displays on dash and is opperated by a dial to the left of the steering column. the center diff lock is operated by a button in the center dash and locks your center differential, making your front and rear driveshafts turn at the same speed. the front and rear differentials lock either your front or rear or both differentials making each wheel on the same axle turn at the same speed. all of these features are for increased traction in off road and wet conditions and situations

well don , if this is a 4wd , actually even if it wasn't i show it to have locking diff(s) , if you have 4wd i show you to have a switch and a light somewhere on dash display indicating if it is locked in or not . , if you look at the passenger side of the rear differential you might see some electronical gizmo attached to it . i recently worked on a lx470 , it was awesome , i cracked the woodgrain cover around the power window switch , ouch , it cost $500 just for that little piece of woodgrain , lexus is very proud of their parts , lol , enjoy that vehicle . i would sure appreciate a FIX YA vote . thank you .

J5

I had the same problem on a recent trip to Mozambique.I found a very knowledgable mechanic in Komatipoort! He says it is always the left rear CV that works hardest when towing a heavy trailer / boat etc. A circlip works loose inside the diff...he repaired mine in less than an hour and it cost me R450-00 including the new oil! He also bent the new circlip slightly oval to prevent future occurances.

Do not drive like this for a long period without having it fixed.!

Regards

Stan Westman