Fully Leased | 3390 Mt Diablo, Lafayette Portfolio Date: June 2018Labeled: Office Leasing & SalesSize: 20,882 SFCity: Lafayette 100% Leased | 3390 Mt. Diablo | June 2018. Our East Bay Office Team is proud to announce that 3390 Mt. Diablo in Lafayette is now fully leased! The team successfully took the large single-tenant space and leased it in four separate parts.