Engine casing - Gear cluster needle bearing track shell
Indian. Good quality, made by SIL Lambretta
This is knocked into the casing and should be a tight fit, the needle roller and gear cluster then sit in it.
To get the old track out you will need a drift and use hydraulic pressure, as described in the advanced section of Stickys manual. Here is a link to the tool: http://www.lambrettaupgrades.co.uk/apps/ webstore/products/show/3700321
Price includes VAT @ 20%