How far in should the Slip Yoke be....904

The amount the slip yokes ground hub area is inside the trans depends on the overall length of the slips ground hub area.

When you take the measurement just bottom it out and bring that and the slip you used to make that c to c measurement to your local driveline shop and they'll make the adjustments you need, or speak with your local driveline shop and ask them how they want it measured.