Two prominent Greater Des Moines businesses have made the list of the top 600 specialty contractors compiled by Engineering News-Record. Des Moines-based Baker Group, which is celebrating its 50th year as a mechanical contractor, ranked No. 201 on the list, based on 2012 revenues of $84.9 million and pending contracts valued at $94.5 million. Architectural Wall Systems Co. of West Des Moines was ranked No. 317, with revenues of $49 million last year and new contracts valued at $28.2 million. The company ranked among the top 14 in the country working in glazing and curtain walls and the top 20 that handle sheet metal. Seedorf Masonry Inc., which is based in Strawberry Point and has operations in Des Moines, was listed as the third-largest masonry contractor in the nation and ranked No. 375 among all specialty contractors. Other Iowa companies making the top 600 list were Interstates companies of Sioux Center, No. 166; Tri-City Electric Co. of Iowa of Davenport, No. 215; Thompson Electric Co. of Sioux City, No. 378; and Young Plumbing & Heating Co. of Waterloo, No. 434.