47-55.1 55 years ago I was given this USAF 54 3100

[mongocanfly]

The LS swap is becoming the norm when upgrading engines now.these are the late model gm engines starting around 1999..also referred to as 4.8, 5.3, 6.0, 6.2.. they can have a ton of miles on them with very little maintenance..not uncommon to have 300000 miles on on...you can buy a used ls engine with 150000 miles on it, stick it in your truck and not worry about it.around here i can pick up a 5.3 with 150000 miles on it for around $800-1000...i wouldnt use a small block with 150000 without a rebuild...nothing against a smallblock but with a LS your getting a more modern engine,more power, fuel injection, ,and better fuel economy.. there's tons of information on here about doing the swap..I'm just throwing that out there as a option..oh and ad stands for advance design..which are trucks built between 47 and 55.1 the next gen trucks are called tf or task force.

[Softpatch]

sorry thought this was another what should I do with my truck thread..

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LS3 swap. for the win.!
Get the running gear out of an avalanche 99-04
cheep eazy build 4x4 Fuel injection overdrive thats why every ones doing it
make great power sound cool
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back in the day we did the crate motor swaps because thats all there was
cheep ezy to get now... Forget about it.... LS3 super simple
and they will go 300,000 miles