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Old 07-15-2014, 01:57 AM   #3
Bowed
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Re: Just bought a 1979 1/2 ton 4X4 short bed...

350's are internally balanced and 400's are externally balanced . For the 400 you can look for weights on the engine side of the flex-plate and a balanced / harmonic balancer , which is usually done in the form of a cut or notch on the backside of the balancer . 400 casting #'s are 330817, 3951509 and 3951511 . If it has 3 freeze plugs each side it is 4 bolt and 2 freeze plugs each side are 2 bolt on the 400 .

Last edited by Bowed; 07-15-2014 at 02:03 AM.
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