Sears began to convert the Western Auto stores to the new parts-only Parts America format by eliminating the automotive service bays. By 1998, Sears almost finished converting the 600 remaining company owned Western Auto stores into Parts America branded stores. By the beginning of 1997, fewer than 850 company-owned stores remained. At that point, the associate stores were the bread and butter of the company, with their more diversified name-brand lines including appliances, electronics, hardware, bicycles, go-karts and outdoor equipment/parts, and their reach into small-town America. Sears removed National Tire Warehouse and Tire America from Western Auto to form a new company called National Tire and Battery, which Sears kept until 2003. From 1991 until the end of the 1997 season, Western Auto sponsored NASCAR Hall of Fame driver Darrell Waltrip's Winston Cup race team. The specialty retailer also sponsored Al Hofmann's Funny Car in NHRA from 1994 to 1997. Advance Auto Parts merger After weeks of speculation in 1998, parent company Sears sold the remnants of Western Auto to Advance Auto Parts of Roanoke, Virginia. The business deal was not quite what experts in the after-market automotive industry expected. Specifically in return, Sears Roebuck became "one of the largest shareholders" after obtaining a 40% stake in Advance Auto Parts, and by merging their two store networks, which included Western Auto's wholesale and retail operations. More precisely, the existing store network of Advance Auto Parts, comprising 915 stores in 17 U.S. states, merged with 590 U.S.-based Parts America Stores in addition to 40 Western Auto stores in the Commonwealth of Puerto Rico. The merger between Western Auto and Advance Auto substantially expanded Advance's network to over 1,500 retail stores in 36 states. Additionally, Sears Roebuck received a cash payment of $175 million USD, while Advance Auto's investors provided a further $70 million USD directly to Advance. Freeman Spogli & Co. organized an investment fund that was among the group of investors that provided Advance with the $70 million cash infusion. Despite the 40% acquisition by Sears Roebuck, both companies maintained their Standard & Poor's "single-'B'-plus corporate credit rating". Analysts continued to speculate on the "financial flexibility" of Advance Auto at the time expecting the company to "take advantage of other opportunistic acquisitions". A few of the associate stores converted to Sears Dealer stores. The remainder of the company-owned stores, located primarily in the eastern United States, were then converted into