Using shortened block or tract numbers in the Plan Components Report is very easy. All you have to do is create a formula field (which you call Name) that contains the information you want displayed. For example, to show the block group and block number of a block (the last 6 digits of the 15-16 digit code), you would do the following:
Now when you run the Plan Components report, 1234 will appear instead to
the right of BLK instead of 190011234561234.
To show only the tract for the Census Tract layer, make Census Tract and use the formula substring(Tract,6,10). In this case, 123456 would appear in the report rather than 19001123456.