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2008 silverado 1500 lt. want to swap 5.3 to 6.6l duramax.

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The duramax weighs basically triple what a 5.3 does, so remember that.


Everything will be custom. A few guys have done it but it's a very lengthy process. Have to make a new crossmember and motor mounts, need to run a aftermarket suspension setup with coil overs to handle the weight. Then you have to figure out what transmission you need/want to run with it and make custom mounts for that too. Whole entire new fuel system for the diesel engine, intercooler setup, larger radiator and so on.

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I know of an old Chevy dualy with 12 valve conversion years ago. And a ram charger with a 4 cylinder Cummins. He got the engine from us. Drove that thing for years delivering parts. In this case it’s too new. I’d go with a modified 5.3. It’s more straightforward probably way cheaper.  

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  • 2 weeks later...

It can be done. The body is same on a 2500/3500 so the engine fits, it's just making it fit the frame with modifications and grille. Aftermarket radiators and intercoolers would need to be used.


Here is a build thread on a 2001 truck from years ago. Stuff starts to happen on page 4.



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On 12/29/2022 at 8:28 AM, 64BAwagon said:

I would bet theres nowhere near enough room under that hood to jam a 6.6L into that chassis. Especially when you consider the radiator and intercooler sizes. 


Duraburb does 1500 conversions with those motors.  When they're done, it all looks stock.

Edited by swathdiver
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