GameShark Codes for:

Gradius III and IV

Effect                                   Code

(M) Must Be On                           EC878D781433BDF8 
 
Infinite Lives- Gradius III              4D97937A1456D7A5

Infinite Lives - Gradius IV              3C20E3301456E7A8
  
Hi Score - Gradius IV                    1C20E32C17E9C70C
  
Powered Up Ship - Gradius IV             DC91832814CD4667
                                         4C20E2661456EBA2
                                         4C20E2681456EBA5
                                         4C20E27C1456E79D