My starter is going out on my 1996 318ti. I would like to get on from ebay and need to know if it needs to be a specific model or does a starter for this car also fit other models?

No, a starter from a 2008 Ford Escape will not fit onto a 2008 Ford Ranger. The starters are specific to each vehicle model and are not interchangeable. The starter is responsible for delivering the electrical current necessary to turn the engine over and start the vehicle, and the design of the starter is different for each vehicle model to fit in the specific engine bay and connect to the battery and solenoid correctly.
If you need to replace the starter in your 2008 Ford Ranger, it's important to use the correct starter designed for your specific vehicle model to ensure proper fit and performance. You can find the right starter for your Ranger by checking the owner's manual or by contacting a Ford dealership or auto parts store.

The size of the bolts that go on the starter of a 1995 Jeep Grand Cherokee Laredo will depend on the model of starter you are using. In general, most starters use bolts that are M6, M8, or M10 in size.
To determine the size of the bolts you need, you will need to refer to the manufacturer's specifications for your particular starter. You can usually find this information in the documentation that came with the starter, or by contacting the manufacturer.
It is also important to note that the starter bolts may not be the same size as the original bolts that came with the vehicle. If you are replacing the starter, make sure to use the correct size bolts as specified by the manufacturer of the starter. Using the wrong size bolts could result in damage to the starter or the vehicle.

Could be the flywheel has been damaged. Also the starter might need to be shimmed. Take the new starter out and look at the teeth on the gears in the starter and the flywheel housing. See where the damage is and you can tell if you need to shim or replace the flywheel.

It will take many pages of instruction for someone to tell you this.
I can but sketch it.
For detailed instruction, you will need to go to a public library or a car parts store and get a repair manual, they are year and model specific.
Disconnect the battery.
Find the starter and unhook the wires.
Unbolt the starter from the motor.
Replace the starter and bolts.
Replace the wires.
Hook the battery back up again.
God bless your efforts.

there is a relay, but there are several other possible reasons for this condition. The safety interlock may have failed open, or it could be your security system too. I would need to know your model, year and engine size to check the wiring diagram.

Please see my tip at http://www.fixya.com/cars/r6222268-engine_doesnt_crank_turn_over . These are generic instructions. If you get stuck or need specific instructions for your car, please get back to me with model, year and engine info.

Need to know model to offer specifics.
You say there is power to the starter. I presume that you checked both the cable and the trigger wire at the starter so you know that the problem is not the immobilizer theft prevention circuit.
On most 6-cyl BMWs, removing the starter involves removing the intake manifold. It is a real PITA, but it is a good time to check and clean a lot of other stuff that you have been putting off, like cleaning the PVC valve and the idle air control valve and replacing vacuum hoses and those leaking power steering hoses.

need a specific model and model trim (dx, lx, ls, ss, ect) also if its becuase your not getting power to your starter, check the solinoid between the positive cable from your battery to your starter.

How many wire are going to your starter? 2, 3, or 4?

go to autozone.com and there is some free repair information or you can buy alldata repair manuals online for almost any specific car