IRS.
Equal length axles, unequal length stub-axles.
Need the unequal length stubs to help center the engine.
Want the engine as far forward as possible so the drive-shaft will be very short, which limits the angle.
Want to eliminate the VW trans and axles entirely.
UPDATE:This might do it for me, particularly if I can just shorten the long side the same distance as the FJR1300 offset?
7.5" ring gear puts it in between Nissan (Datsun) R180 and R200.
The IFS diff in 85-95 Toyota 4X4 pickup and Four-Runner.
It has one short stub axle and one longer one.
For a narrow diff simply mill the side with longer stub 6mm and use same seal as short stub side.
Plug in another short stub and you have a compact narrow,strong IRS unit. I don't know if the 6 bolt pattern is the same as Nissan R200 and R230.
You could use the same type adapter to VW type 2 or Porsche 930 CV.
Very common and cheap in junkyards.
79-95 2WD rear 7.5" straight axles had ratios of 3.15 and 3.36(rare) 3.42 and 3.58 (more common) 3.73,3.91 and 4.10(most common).
Tru-trac Torsen type or 4X4 lockers are available for this diff.
Remembered this from another forum, old post so it was hard to find.
This may help with other BEC's since you could also us it for a middy with the bike trans.
Just flip it to get the rotation you need.
Lets see if I can post a pic of this Toyota part.