[Electric Land Cruiser]

Super excited for your project as it's similar to mine! My buddy has an original Scout SII! He's in the process of restoring it, it's not even completely rusted through! Looks like your truck is a pretty good starting point too! Cool matching hardtop.

Some ideas maybe or maybe you haven't thought of:

-Maintain the stock transfer case but ditch the transmission. It's possible you can find a "doubler" that matches your transfer case. Doublers are used to ultra-low gearing on 4x4 trucks with massive tires and basically "double" the reduction ratio into the transfer case. This is what you want in order to direct drive with the LEAF motor because you can ditch the transmission's dead weight and better utilize the transmission tunnel space possibly even fit the motor there and have an entire engine bay for batteries.

-Keep the stock transfer case so you can shift to Low Range and go offroading or pull trains or whatever sounds most fun to you.

-From my experience driving EVs I expect my 4x4 EV to get 2mi/kwh on a good day. That means to go 100 miles, it needs 50kwh of usable capacity. Something to think about. I plan to use a single LEAF battery to start, and then add more as I go because they are the cheapest option. I do not even know if multiple BMSs can be run independently like that but I think they can.

-Download the CAD file for the adapter plate and wait until the coupler adapter is available for purchase here: For Sale: em57 leaf motor couplers then just need to have a driveshaft shop build a custom shaft to match and build some motor mounts!

 

[Electric Land Cruiser]

Keen to see your cruiser build too, all the rich kids parents had those when I was a teenager in Australia 😂

I thought about this but I talked myself out of it. I wasn't sure how to go about the gear reduction and didn't realize there were good options out there. How do I go about calculating what gear ratio I would need? Are there generic options that would do what I want? Would be amazing if I could fit the whole motor and gearbox assembly further back to make room for batteries. The only down side is I do like the idea of being able to slam on the clutch as a safety measure

You can make it complicated or not complicated. The Nissan LEAF has a total ratio of 8.2:1. My Land Cruiser has a final drive of 4.1:1 so if I want to match the LEAF's top speed of 95MPH at 10,000RPM then it's just a simple 2:1 reduction (4.1 x 2 = 8.2:1). But since it's a heavy truck and 95MPH is way faster than I need I decided on a 2.7:1 reduction which gives me 2.7 x 4.1 = 11.07:1 and a top speed of 70MPH with stock size tires.

You can also just cross multiply using the LEAF's numbers:
95MPH/8.2 x 11.07 = 70 MPH

You'll likely be limited by what is available to bolt on to your truck but anything from 2.5:1 and 3:1 additional reduction should work for you. Also depends on your truck's differential ratios.

I do like the safety aspect of a clutch, with a transfer case you can simply shift to neutral, also. Not as natural or fast but just as effective.

THIS is what I've been looking for. So what exactly would I need to connect this coupler to the gearbox/doubler?

You would need to have a custom driveshaft built. Also that coupler is only halfway made, it's designed to be drilled out to bolt on a specific drive coupling but instead of that my plan was to have a machine shop weld or bolt on a common sized driveshaft yoke.