What could be the final jackup oil drilling rig fully produced at LeTourneau Technologies was walked to the Mississippi River’s edge over the weekend and should be floated downriver by month’s end, company officials said Monday.

The $150 million Joe Douglas 240-C class shallow-water rig, under construction since 2009, will depart for Sabine Pass, Texas, by Aug. 31 where the rest of the support legs will be added, plant manager Bo-D Massey said. Its first assignment is in the Gulf of Mexico, according to filings with the Securities and Exchange Commission by LeTourneau’s former parent company, Rowan Companies.

In June, the Houston-based oilfield services company completed a sale of yards in south Warren County and Longview, Texas, to Milwaukee-based Joy Global for $1.1 billion. At the time, the 125-year-old company, a major provider and service outlet of equipment for surface and underground mining, said combining wheel loaders and drilling-rig equipment already produced at LeTourneau with its own line of surface-mining equipment represented “a compelling opportunity,” said CEO Mike Sutherlin in a statement.

The rig, which can drill in 400 feet of water with 491 feet of leg length, was used as a trellis of sorts when the plant flooded during the Mississippi River’s record rise in May — which also delayed its departure from Vicksburg. The schedule appears to be full-steam ahead to be delivered to sea in September, Massey said.

“We’ve already been launching,” Massey said. “We began last Monday.”

Joy has a target workforce of about 250 once orders under way are complete, said marketing officials who visited the local plant in June. Jobs have been shed after many of the approximately 600 workers returned to the job once floodwaters subsided and the access road reopened June 20, a month and a day after the river crested in Vicksburg at 57.1 feet, 14.1 feet above flood stage and 1.3 feet higher than the Great Flood of 1927.

Whether the yard would produce full-scale rigs is uncertain, though making “rig kits” — most often, the rig’s leg components, jacking system and other parts — are a possibility, said Mark Sanders, vice president of corporate marketing, during the visit. On June 16, a week before the sale closed, LeTourneau announced it had inked contracts for kits and licenses to build two mobile jackups for KS Drilling Pte. Ltd. They will be built by Chinese shipbuilder COSCO Shipyard Co., based in China’s Nantong province, and be delivered to sea by 2014.

Joy plans to release its third-quarter earnings Aug. 31, coinciding with the rig’s expected departure.