Class 8 truck sales were at near-record levels again in May, according to manufacturers.

The May total of just over 25,000 trucks is up 20 percent from May of last year, and is the third straight month of record or near-record sales.

Some industry analysts say it's further proof that a big pre-buy is going on – with fleets and individuals replacing aging equipment now, rather than waiting for the more expensive 2007 Class 8 trucks.

In May, Class 8 sales were led by Freightliner, followed by International and Peterbilt, respectively.