The only issue with rebuilding is you won't end up with all GM parts. Not saying others are bad but it does make a difference. Now, I don't know where you are located. I know here, in PA, rust destroys vehicles because of products used on the roads during winter. Once a vehicle hits about 10 years old, frames, floors, and structural components really get bad.
So if you were to do it and you live in this type of area, make sure the foundation of the truck is good. The GM vehicles around here are starting to have frame problems. Next, you have to keep in mind that everything on the vehicle has a lot of miles. Components such as bearings, sensors, modules and so on may work today and be bad tomorrow. That is one of my biggest concerns because to replace everything to rebuild the vehicle, it would be cheaper to buy a new one.
In my mind, you would most likely be better off finding one with low mileage.
Let me know if you have other questions.
Monday, March 30th, 2020 AT 7:32 PM