Thanks, kind of what I thought. Leslie's does not carry split nuts. The cracked nut shows Hayward model SP-1500-G. According to INYOPOOL website, the specs are:
DIMENSIONS 3" L x 3" W x 1.25" D
ALTERNATE PARTS# SP1500G, SPX1500G
Product Description
Nut, Union, 1-1/2" FVT, Hayward "V" Thread...