The GT's are built on many years of proven parts. I don't know of anything on that setup that is prone to going out at about 70k or at 120k or even 150k.
Normal wear items that may need replacement now or in the next year or two.
Clutch
Shocks/struts
Spark plugs/wires (these can wait a while)
Battery
Tires
The manual transmission is a little weak, and the automatic transmission is a little slow. Take your pick.
As far as tires go, I liked my Nitto NT-450 Extreme's on my 87, but they did squeal too easy.