Introducing an exceptional investment opportunity in Southeast San Diego, just blocks from Interstate 15 and Imperial Avenue. 3517-23 J St is a well maintained 4-unit multifamily property featuring four 2 bed / 1 bath apartments (2,912 SF, built 1959) on a 7,071 SF RM-1-1 lot with off-street parking in front and a large open rear yard. Three units are leased with tenants reimbursing water through a RUBS program, and one unit is vacant. This is an ideal for an owner-user or a buyer looking to set rents at market from day one. What sets this property apart is the MASSIVE development upside: a full architect-designed plan set is in hand for four detached 2 bed / 1 bath ADUs in the rear yard, offering a clear path to double the unit count to 8 and dramatically increase income on a rare, deep infill lot. Current rents sit well below market, providing additional value-add upside even before any construction. Offered at $1,500,000, this is a compelling opportunity for the investor looking to capitalize on San Diego's strong rental demand and build long-term value. Seller is completing a 1031 exchange; buyer to cooperate with seller's exchange at no cost to buyer.