Elon Musk’s bluster, it turned out, lasted all of one day.

A deeper examination of Musk’s boasts about the Tesla Semi revealed little information about two key items — the price and weight of the semi.

The lack of the key data left a wide open left lane for shares of truck makers, which gained back on Monday some of Friday’s losses.

The truck companies, in the wake of Musk’s press event late Thursday — highlighting the cost advantages of the electric semis — saw their stock tumble on fears that Tesla would quickly steal away market share.

The Tesla Semi, the electric car maker’s first truck, is expected to go into production in 2019.

The Tesla Semi is expected to have a 500-mile range and highly touted ability to go 0-60 in only five seconds.

Walmart, on the spot, pre-ordered 15 of the trucks.

But then some Wall Street analysts couldn’t determine the Tesla Semi’s payload capacity — in addition to its cost and weight.

Shares of Navistar International on Monday rose 1.5 percent, to $38.18, after falling 3.5 percent on Friday; Paccar shares gained 1.5 percent, to $67.70, after easing 4.3 percent on Friday, and Cummins shares were up 39 cents, to $159.80, after falling 4.6 percent on Friday.

Tesla shares on Monday eased 2 percent, to $308.74, after rising 0.8 percent on Friday.

“Tesla cars don’t need to prove an economic case to their buyers, but Tesla trucks will,” Stifel Nicolaus & Co. analyst Michael Baudendistel wrote in a research note. “Assessing the potential return on investment starts with price.”