Radio noise below 30 mph

[KB0OU]

I am getting a noise on AM radio with weak station when my 96 gets below 30mph. Noticed it while listening to Rush Limbaugh while out in the boon docks, we have those in SW Missouri, in the hollers.
The noise goes away above 30mph, I have tried putting load on alternator etc. , does not seem to be charging system, I think it could be some control signal.
Thanks for the help,
John

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96 CC 4X4 2500 SLT AUTO transmission, PrimeLoc, ISSPRO EGT Boost transmission Temp, GUTTED CAT, 150,000+ Miles still goin' strong, Lots of Ham Radio gear, NO IGNITION NOISE!!! Love my diesel!!! # 8 TST Fuel Plate.

 

[adiabatic]

Did it just recently become a problem? Or was it always present? I have not noticed it.
I will have to listen to Limbaugh I suppose...
N7DAL

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1997 4x4 CC 5spd, CPL1553 pump, Horton fan, Sport headlamps, Optima RedTops, 98 shift levers and console, RS5000 shocks, red light on dash (vol. FF)... .

 

[illflem]

Maybe the noise is there all the time and you just can't hear it once that 12 valve is revved up. I've never had a problem with mine.

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95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(work truck)
95 3500,5 speed 3:54,Driftwood,Banks&Psycotty,34,000 GCVW apple and tractor hauler(works harder truck)

 

[The patriot]

Maybe it's a vast "left wind conspiracy"?
Possibly a poor attempt at jamming from Cuba? #ad
The Chi-Coms? #ad

Is this the only radio you have on when it happens?