Part list :

GT750: GT750-K-Bm

GT380: 01 – Suzuki GT380 GT 380 Parts List Diagram Manual 1972-77

Service manual: 

GT750 : GT750 Service Manual

GT380: 02 – Suzuki GT380 GT 380 Service Manual

Carburetor :GT carb sevice manual

Specifications:

Spec: 72-77: Suzuki GT Series Specifications 1972-77

Service Bulletins:

GT & T series: 08 – Suzuki GT & T Series Factory Service Bulletins

http://www.ozebook.com/compendium/techbuls/index.htm

Anti surge jet bulletin: GT-36