[71Dragtruck]

He's saying you don't need the center to mock up the chassis, all you do is slide a piece of tubing over one axle, then install it with the tubing at the end (bearing installed on the axle of course) and then install the other axle on the other side sliding the tube so that both axles are now inside it and the tubing is in the center of the diff, now retain the axles with the retainer plates.

You can now mount wheels on it and put the weight of the chassis on it with no need for a center section untill you get the one you are going to use. To get a mock up center section to work you would need a 35 spline spool or diff of some sort to fit your axles, not worth the effort when you will likely be purchasing a complete built center when the time comes.