Retailers have gotten away from doing conversions because of liability. The correct suggestion is call your gas supplier. Sears should be able to get the conversion kit, in fact you may be able to order it yourself online from Sears.  It isn't that difficult. Depending on the dryer it may be as simple as changing an orifice and a regulator spring

Or it may need a few more parts

See www.doityourself.com.