Trevor
The drawing calls for the spline to be three inches & the overall shaft length to be 6 & 5/8" from the shaft end to the centreline of the Spicer joint, so 54mm or 2" spline length is therefor too short, maybe an owner might confirm this to be the case.
The female spline length in the hub is about 5", you might experience more wear with the 2" long male spline considering the spline diameter is 1.5", I would think it safer to have the correct length spline it will be also better supported!
Robin