[special-K]

First of all it,there is nothing you can do to a truck or car that would make it a muscle truck or car.The term muscle car refers to factory-built hi-performance cars built from production stock.In other words,a sedan or sport coupe your grandparents could have been driving.For instance:GTO=Tempest with big motor and all the go fast goodies.
There never was a term "muscle truck" known until more recent years.Muscle car came along once these cars became a thing of the past by the low-performance`80s.But,these trucks are from the height of the muscle car era and I consider a BBC/TH400/posi/tach/bucket seat shortbed to be a muscle truck.I used to think that truck would have to be a CST/Cheyenne model.But,comfort and appearance options really don`t have anything to do with it.It could have a 350/3spd/tach/4.10s/posi/manual steering and be a muscle truck,IMO.That truck was built with performance in mind.The first thing many did was to massage the motor into a big power 350.Yes,after the factory.But,that`s how it was back then."Muscle car" is an era and back then as many all out muscle cars would go directly into the shop for some performance enhancement as left original.But,it`s still the vehicle you start with.I`d say these trucks,with certain options,could fairly be referred to as muscle trucks.Take`68 and line these up:
*Nova SS396
*SS396 Chevelle
*SS396 Camaro
*Impala SS w/427(or 396)
*Caprice w/396(or 427)
*CST/10 shortbed w/396
It fits right in there.It may not be the higher output motor.But,that truck was built or performance,not work.A 350(or 302) would fit in there,too.

I bought a truck about 25 years ago.Two brothers ordered identical trucks:
Shortbed Fleetside,red w/white top,396,bucket seat,tach,3spd,HD clutch,manual steering/brakes,posi(both changed to 4.10s,headers,intake,cam,head work,Mallory dual-point).Mine had Cragar S/Ss and he the other ran aluminum slots,both 8s & 10s.They were daily drivers,at first,as well as take to the track rigs.Those guys didn`t want a car.They were hot rodders and they liked trucks.They got all excited when GM offered the big block and ran on down to place their orders for the muscle car of their dreams...a shortbed truck with a big motor.