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.