Converting a 72 K10 longbed

Hi all,

I have a 1972 K10 longbed, currently has a 2.5" lift and powered by a 396/TH350. Originally a 350 truck. I'd like to know how feasible, economical, and durable a 6.2 or 6.5 conversion would be.

Basically, I'm trying to convince myself that if I drive the truck enough, I will save enough on gas to make it worthwhile. Hoping to maybe drive 5k miles per year, at best.

Right now the truck has the gas tank behind the seat and also two saddle tanks under the bed, so it can hold something like 50 gallons of gas. A secondary motivation for my interest in the 6.2/6.5 conversion is that diesel fuel has this wonderful quality of not exploding when someone sideswipes a pickup with saddle tanks ...

Thanks for any input or comments, or links to a build on a 67-72 4x4.

Well, the most I think you can expect to save is about half your fuel costs, so what do you think your payback is going to be? It'll be a slug compared to the 396, but someone will probably give you good money for the porcupine motor.

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Originally Posted by JohnC

Well, the most I think you can expect to save is about half your fuel costs, so what do you think your payback is going to be? It'll be a slug compared to the 396, but someone will probably give you good money for the porcupine motor.

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Probably $750 per year tops. So if the conversion costs $7500, it pays off in a decade, if it costs $3750, it pays off in five years.

The 396 is pretty old so I doubt I'd get more than $500 for it. My best bet would be to try to find someone with a running 6.2 and do an even swap, but that's a pretty fine needle to thread trying to find someone that has a 6.2 and wants a 396!