How can I know if my Dana 44 rear axle is a 19 or 30 spline?

Finally after calling Yukon Gear and over 35 emails to Seven Spring Custom/Complete Off Road 4 X 4 reluctantly agreed to take the parts back. Even though I told him I spoke with a senior tech at Yukon who said the parts that were sent will not work, the sales rep still insisted they would and Yukon did not know what they were talking about. I asked who was going to pay for shipping and he said either you pay for the return shipping or get charged a 20% restocking fee! So they have been shipped and should be there by Thursday. Now I wonder how long it is going to be till I get my refund! My plan now is the get a 3 series Posi Loc and install that.