As stated above check the frame very closely.
I went looking for a newer replacement for my 98 Silverado (Last year of the old style).
and ran into 2 in the same day with rotted out frames , (1 was a 99 the other an 02) 1 was actually broken, and this was about 4-5 yrs ago so now they are even older and i'm sure lots more rotted ones.
The ones i saw were both rotted by the rear wheels around the area's where those big round tubes go from one frame rail to the other, they were probably rotted in other places also but when i saw that i just stopped looking at the vehicle and left.
I also saw one not too long ago that was rotted real bad under the cab area like in the second video.
Companies actually now make and sell these sections so you can cut out the old rotted sections and weld in their new sections. (Thats how common it was/is.)
Since then i have found out that is not the only bad area, the whole frame is prone to rotting and breaking including where the body mount's are.
See the below video where he put huge washers in the mount holes and fixed other sections also.
Neither of these 2 video's are as bad as the 2 i had looked at a few yrs ago.
If i remember correctly they blamed it on bad mexican steel at the time, and as far as i know gm never made good on any of them.
Google 99 and up rotted Silverado frame for more info.
Ps, all the break lines and i believe fuel lines also rotted out real quick for some reason.
I would suggest buying the newest you can find in your price range, but even some of the newer ones have had frame problems .
Just as a side note my 98 2500's frame has 0 rot, but it also had a somewhat easy life and the body is pretty rust free also.
Good luck.