I appear to have opened up a new can of worms, I am doing an engine conversion putting a subaru ea82 in my old bus, however the adapter kit flywheel I have purchased accepts the 228mm clutch and now I have my 2litre motor out of the vehicle it has a 215mm clutch and a 5 rib 002 box, can I just get a 228mm clutch or are the input shaft splines different? I suspect the latter. I thought the 2 different boxes were interchangable, though. any info would be appreciated

The input shaft from an "1800 5-rib" 002 box is identical to a 2lt "6-rib" 091 box.

***Problem will be that the bell housing is deeper on the 091 to make room for the larger diameter clutch.
The 091 starter is different also, to match.***

You can change the bell housing and starter motor easily enough,
or trade your adapter kit for one that suits the 002 box,
but RPM on the highway will be ugly.