I just installed the diffs with Kershaws kit, as you stated the shaft was a tiny bit too long. To make it work i simply ground down the shaft coming out of the transmission, took me a couple minutes with the dremel.
The diffs themselves look great, fit and finish were also impressive.
and now for the picks!!
Toys:
Slash with VXL
E-revo with MMM/Teckno Nue 1515/1yf running 4s and 5s