Most if not all questions can be answered by reviewing the Cummins install manual I linked. We didn't have the advantage of that pearl of wisdom,it was just released in January.
On transmissions, we used an automatic. The truck is anything but slow. The two other vehicles with a 2.8 mated to a 6l80e are both owned by Cummins. Those trucks both have the torque converter swapped out for a higher stall (2500 rpm) converter. Since the engine makes max torque @ 1500 and max's out around 3k we decided that didn't sound right and stuck with the stock one. The combination of the stock 6l80e, 1.2 tcase (used a d2 one and went GPS Speedo), and 4:10 gears with 35 inch tires seems to work nicely. smaller tires and stock diffs would have similar gearing. The fellow we built the truck for is still playing with shift points in the software but this transmission also "learns" as you drive it. Ie the more miles you put on it the better it works. As it is now, you do not even feel the shifts. He's switching back from the GM shifter it left here with to a Lokar because he likes the traditional/minimalist "look" more. That said, if anyone wants a Ashcroft console that is uncut for a shifter hole, get in touch as it won't be getting used. This truck was built to be wheeled so filling a 1/3 of the cabin with a console was decided against.
Engine cost is $8999.
If a Cummins auth installer like me buys it and gives Cummins the make, model, and vin we get a $300 discount (thats it) which pretty much only covers shipping from the Cummins warehouse in Tn these ship from.
Adapter cost to a rover 4cyl bellhousing is appx $2200. I gave Chris and Kevin @ Axis two trashed transmissions for templates. Contact those guys for a pilot bushing and modified flywheel, and adapter.
I'd suggest only using the heavier duty 130 clutch assembly.
Radiator/Intercooler- on your own here. Heritage Driven put an intercooler in front of the stock v8 radiator in a disco 1.
I've posted pictures of what I had made to spec but that special sauce costs $2k.
The engine ecu has the provision to controll adn electric fan. It kicks the fan on @ 190 degree's via a switched ground lead from the ecu. IE you wire up your fan with a relay and the ecu asks for cooling when the engine temp needs it.
People have emailed, texted and pm'd asking if Tdi stuff could be made to work ? Maybe, but the plumbing/hoses needed to make it work would look like Medusa's hair. Can a v8 radiator be made to work ? No. You need an intercooler and the v8 fills the entire space between the wings leaving no passage for the boost hoses.
My thoughts on this are why half ass the all important cooling system when you have a brand new everything else ? Do it once, do it right.
Wiring- The Cummins comes with its own harness and they indicate the ECU should be mounted in the engine compartment. The portion of the loom that needs to enter the cabin fits nicely through a stock defender bulkhead grommet. I placed the Murphy gauge(canbus gauge that allows you to scroll through all the functions and also displays any fault codes should you throw one) in the stock defender binnacle. Ie totally non- invasive install.
Oil filter. This one is on the installer. An oil filter needs to be where you can get to it and ideally where it can drain without making a huge frigging mess. I mounted it to the defender frame using a bracket i made up that uses one of the frame to bulkhead bracket bolts and two of the through frame crossmember bolts. This held the filter up above the bottom of the frame rail just in front of the trans crossmember.
Drive line. I mounted the tcase in the stock 97 NAS 90 spot using the factory brackets. The drive shafts I used were both solid ones, Ie not tubing like the lame ones used in defenders. The front I think was from a D1 and the rear was from a Classic. Both were front drive shafts.
Parking brake, I drilled and tapped the D2 case and used the original 1991 defender parking brake assembly.
Brakes-we used all new NAS 90 parts to include stainless lines from Rovers North. Total overkill, but make sure you have great brakes as the truck is going to move out.
Exhaust. I kept the particulate filter/cat and had a custom straight pipe made. Each install will vary here with the transmission chosen. Mine was 2.25 pipe that ran paralell to the driveshaft and then dove under right in front of the transfer case and then followed the stock route to the rear.
Fuel- I mounted the Cummins fuel filter in the same spot Rover mounted the 2.5 and 200tdi filters, on the bulkhead on the right side.
Steering- stock, had adapters made @ the steering box so I could use the universal AN fitings and then had my local Parker store make the lines. We used an adjustable panhard rod but this was because of the 3+ inches of lift the truck has. The stock steering res works fine.
That leaves engine mounts. This will vary with what trans you decide to use and what engine your truck has now. I realize not everyone has a mig and the ability to work with steel but I truly would not let this part of the conversion be a deterent. If you are using a rover trans, Chris and Kevin @ Axis will have an engine side mount that will match up with your existing chassis mount.
If you aren't the diy type, or know it will take you years to complete a project like this, send it to us.