You mean that the shaft that goes into the black rubber boot thats right at the transmission?
I've had that happen alot to me on previous suspension instalations.
Its simple, Just hold the axle level and inline with the transmission output shaft and slowly ease the axle away from the transmission, rotate it a little and let it go back. Be patient, eventually it will go back in.
They're ticky.
You still have the wheel hub attached to the end of the axle I assume. As long as the axle goes into the CV housing and you can align the hub with the ball joint pin on the lower control arm it should be fine.
