This is the little rubber vent tube that keeps water out of your Denso starter. If this tube is missing or damaged water can get into your starter motor causing premature failure of your starter brushes and other parts. It's easy to replace. Dodge Diesel 1989-1993. Denso Part# 71-82302
Crossover Part# DENSO 028062-0500, 028062-5150, 028062-5670, HINO 28154-1130A, ISUZU 1811294790, 8943772391