Yes, could be cv joints. Acceleration squats the rear a bit and takes the balls out of their well worn grooves making a racket. I had some once that were fine until I loaded the car for a trip squishing them down from their comfort zone.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.