If you are newer to Lambrettas, it may be a daunting task so we put together this little guide to help you identify what you need:
S1/2 LI: Fits all Series 1/2 models. On TV1/TV2 models you will need to fit an LI handlebar switch.
Series 3 LI: Fits all Series 3 LI 125/150 models. Also standard on early Serveta 150cc models without space shuttle switches. Looks identical to the Series 1/2 but smaller.
Series 3 TV/SX: Fits all Series 3 TV/SX models. Also used on all Italian/early Indian GP/DL models and early Jet200 models without space shuttle switches
Serveta with space shuttle switches: pretty self explanatory. These are found on late Servetas.
Indian GP: These are found on Indian GP headsets, which are wider and distinguishable by the mirror stand-offs on the underside of the headset.
Fork Link Types:
Disc Links: Used on TV175 Series 1-3, TV200, SX200 and Italian GP/DL200 models. Distinguished by the use of a threaded stud on the brake pate to attach the brake plate to the right fork link.
Drum Links: Used on everything else. Distinguished by the use of a stub on the right fork link to retain the break plate.