Moto Guzzi 250 TS, 350 NTX, 650 NTX, 750 NTX, 750 SP, 750 T, 750 XPA, Breva 750, Nevada 350, Nevada 750, STR V750 IE, Targa 750, V35, V35 Florida, V35 II, V35 Imola, V50, V50 II, V50 III, V50 Monza, V65, V65 Florida, V65 SP, V7 Café Classic, V7 Classic, V7 II Racer, V7 II Special, V7 II Stone, V7 Racer, V7 Special, V7 Stone, V75, and V85 models
Thanks to Charlie Mullendore of Antietam Classic Cycle for sending me this information via e-mail. In Charlie's on words:
Transmission breather. The original has a tendency to burp gear oil out all over the transmission when it's filled to the proper level. This fixes that issue.
A length of hose attaches to the fitting and the is routed up high.