Someone in an earlier post (much, much earlier) had suggested using a chambered corvette muffler. If i remember correctly, his description sounded like the sound you're looking for. Of course, there were no sound clips. Check the archives for the post.
RapRap, did you ever get your sound experiments recorded? I'd be happy to host them for everyone to hear.
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'50 Chevy Fleetline DeLuxe ('55 235)
'48 Chevy Fleetmaster coupe ('60 235)
Chicago
http://www.geocities.com/hellfish122
