Not nearly as strong as a 9.5" diff. See blown up fzj80 front 8" diff.
The 80 knuckle balls are larger than a 40/60/mini, but the axle shafts are the same diameter, so you're not gaining any strength there either.
The 80 shafts will mate with the 40/60/mini birfs. The star gear spline count is the same, that's what the question was.
EDIT: it appears matzell and I are mistaken.
Those widening kits @lcwizard used to make almost necessitated a truss, with how much width you were adding.
I had wanted to widen a 60 front to a ~63" width, and bought the kit from lcwizard, but it was cheaper to put a Dana 60 in, so I sold it all. If I *had* to stay Toyota I'd opt for a...