V6 means it has a 3.8 Liter, 6 cylinder engine.
For that same year, the V8 would have a 4.6 Liter 8 cylinder engine. The extra cylinders make more power and this model will consume more gas.
GT = Grand Touring. All Mustang GTs to date, are 8 Cylinder Mustangs but not all 8 Cylinder Mustangs are GTs. The GT package means a few different things when combined with the year/platform it was made. They are 'generally' a little better outfitted, a little heavier, and are Top-of-the-Line for base models before getting into special orders or performance packages or Special Vehicle Team (SVT).
The V6 that you posted has nearly 150,000 miles on it. It is going to need maintenance. One day it will be a fuel pump, the next a head gasket, or some dumb thing that you'll have to come in here and get help to figure out.
So... If you do not own a tool box and have no passion whatsoever for turning wrenches, replacing bad parts, or troubleshooting the odd electrical issue, then I would run to the nearest used honda dealership and find one with similar miles and a clean history.
If you want this thing because you just like Mustangs well... Find a GT and pass on the V6.
This car will need work and you can expect it needs a couple thousand just in preventative maintenance. At minimum, it needs to be gone over by an independent mechanic.
