This item for sale is an excellent condition used Venturi for Mercruiser TKS carburetors.
Mercury Marine/Mercruiser PN: 3302-850423001 
 

Fits Mercruiser TKS engines:

3.0L (181ci) GM	Serial Numbers 1G404114 & Up
3.0L (181ci) GM	Serial Numbers 0L097000 Thru Serial Numbers 0W301999
3.0L (181ci) GM	Serial Numbers 0W302000 Thru 1A0019999
3.0L (181ci) GM	Serial Numbers 1A002000 Thru 1A020543
3.0L (181ci) GM	Serial Numbers 1A020544 & Up