HELP! Shortening my driveshaft

You want to make sure the car is sitting with the weight of the car on the axles. Put a yoke into the transmission, pull it out 1 inch. Measure from the center of the yoke to the center of the pinion on the rear axle. Thats the measurement you want.

thanks you! that is what i was lookin for.! i also did not know that the weight needed to be on the axles before doing this. now i know. should I have the pinion angle set already? i'm not sure the exact process of checkking and setting the pinion angle, but when should I do it?