These medium-duty pintles and gudgeon components are most familiar as "J24 type" with separate pins and welded pintle straps contained between an upper and lower gudgeon strap.
This high strength, easily removed design is excellent for trailerable boats.

Illustrated: J24 lower gudgeon with pintle and pintle transom straps
Note: Atypically, in this hardware series the Pintle attaches to the transom, and the Gudgeon holds the rudder
The difference between the J24 upper and lower gudgeons is that the lower gudgeon is twice as long as the upper gudgeon; see Specification Table
The 81-50 J24 Transom Assembly consists of (1) 81-49 Pin and (2) 81-46 2-Piece Pintle Straps to hold the pin