I suppose it depends on the length, if the driveshaft assembly is balanced, and weather or not the EXT box bearing could serve as that bearing (innitial thought is its too far away). Spitballing here atm. I dunno if this has been done or not.

Its a project Dan! You know….The heads; my buddy is running all salt, all the time. What’ll last longer down here, iron if we’re comparing apples to apples, flush to flush; and not chasing a dyno number.

you can use the shaft for an IMCO box ( which uses the Merc coupler)but you have have the box set at the lowest position ( top holes in the box)

you’ll have to remove the side cover to see where it’s set at

Agreed, I looked at the imco shaft today; and the boxes for that matter. Still a work in progress. I’m not entirely sure boxes are the best fit at this point. I’ve read conflicting accounts.