General Motors Corp. eliminates a second shift at its Shreveport, LA, truck plant and ceases production as scheduled at another plant in Doraville, GA.

GM pulls the second shift at Shreveport on Friday, citing sluggish demand for the plant’s products. The facility builds the Chevrolet Colorado and GMC Canyon midsize pickups, as well as the Hummer H3 and H3T midsize SUVs.

Through August, sales of the Colorado were down 22.5% and sales of Canyon were off 24.4% vs. like-2007, according to Ward’s data. H3 deliveries are behind by 47.9%. GM’s light-duty truck sales are down 23.1% through the first eight months.

Removing Shreveport’s second shift eliminates 798 jobs and reduces the plant’s headcount to less than 800, GM spokesman Tony Sapienza confirms. The plant recently employed as many as 1,847 hourly and salaried personnel.

GM wants to sell off its Hummer SUV division in the wake of a dramatic shift in consumer preference away from gas-guzzling trucks to more fuel-efficient passenger cars and cross/utility vehicles.

GM invested $73 million at the plant in April to add the H3T. GM has built about 1,000 H3Ts at the plant and units just began arriving at dealers. National advertising for the crew-cab truck breaks on Wednesday.

Meanwhile, production ceases as planned at Doraville, which built the Chevy Uplander and Pontiac Montana sport vans exclusively for the Canadian market. It recently employed 1,082 people.

The Doraville closure on Friday essentially ends GM’s participation in the minivan segment, where it struggled to compete with more popular offerings from Chrysler LLC and Asian auto makers.