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How Hard Is It To Convert The Manual Trans Setup In My 1955 Gmc Flatbed To Automatic? The Straight Six Engine Was Swapped Out For A 327 Out Of A 69-70 Impala, And Im Not Sure If The Trans Thats In It Now Can Handle That Engine. If Not A Conversion, If Anybody Can Tell Me What Trannie Will Fit, And With The Least Amount Of Hassle
 

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That big old truck will be a handful going down the road.
You can use just about any automatic transmission from the Chevrolet menu.
I think you might look at a 400 Turbo since you are hauling some freight there. Most motorhome chassis used the 400 and they're hauling everything including the kitchen sink!
That old probably has a "Granny-geared" 4 speed on the floor doesn't it? or a 3-speed column shifted box. Regardless, unless they are wasted you would have to worry about tearing them up except by missing shift points jacking around trying to be Mr. Cool in a one-ton flatbed farm truck (which is not cool under any circumstances). The same transmissions had big Pontiac V8s in front of them when the same truck has a GMC grille and nameplates on it.
You'll have to fab up a simple transmission crossmember and have the driveshaft shortened and a different yoke added to it for the modern trans and vavavoom, you're riding again but not shifting much!
Best of luck, enjoy the truck!
 

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the trans you have now is iron case, it will handle a big diesel even, i would be more worried about an automatic trans stayin alive in that truck, that manual trans will take anything you can throw at it, you wont break it

good luck though
 
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