Air cleaner mounts (are they intact?) or motor mounts could easily cause a rattling sound on acceleration. If it's the motor mounts, the rattle could be the fan hitting on the shroud, check out the fan baldes and condition of the shroud.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.