Good quality Lambretta series 1, 2, 3 & DL/GP stainless steel gear swivel arm, this bolts to the crankcase and the gear cable trunnions sit in the holes. 
 These are a great match to the stainless steel UNI gear swivel pivot posts, these are available here:
 
Please note: this is just the top swivel arm, does not come with the pivot base, washer or circlip.