located Dave's W4 parts book.
The first set of rear weights are 8076D @126lbs. they have 5 holes, 3 for mounting to rim and 2 threaded to mount the 2nd set.
second weight set is 8077D @137lbs. they have 4 holes, two clearance holes to mount to the threaded holes in set #1, and two threaded holes to accept set #3.
however, you could mount a second set using 8076D (first set) by drilling out the 2 threaded holes to clearance holes, or by mounting both sets with a long threaded rod, washer and nut the first set, leaving the rods to stick out far enough to mount the second set.
only the correct police might know the difference!