Can someone tell me what this part is?

Question

I wanted to make something from the "Forbidden LEGO" book and I came across a piece, I don't know what the part number is.

The piece has 5 peg holes, one axle hole, half a gear, last of all I don't know, but in the instructions, it looks like there are 2 half peg holes. What is the part?

Answer 1

This is Technic Gearbox Half. It's very easy to find by searching "technic gear" on BL.

The item number is 32166, and it was available in the early 2000s (specifically from 1999-2002).