main bearing install HELP!!!

I'm new to the sc world,, my question is upon installing my main bearings (part # ms1782p) all the bearings say "standard" but by the indivdual numbers on the bearings I have a thrust, two that are alike and one that is by itself. The one that is a number to itself does have a different cap bearing. How do tell which one is for the rear?????

Use some calipers, and carefully measure without scratching them. The thicker ones go on the rear.