is GSX1100E. The 1100E (that is ET,EW,EZ not ESD or EFE)had rear disc ,box section and twin shox but think your pic is deffo Suzuki wheels although not totally convinced swingarm isn't after market like Ronni sez.Could be the 750 of course but this had an 18" rear wheel where the 1100 and 1000 had a 17".
"I'm not being much help am I ,dad ?"
OK so I've added nothing at all to this convo but this is kinda my era and I love these big ole suzy fours!(Oh and triples of course!)(anyone for tea?!)
Maxie xx