With normal maintenance you should get about 200,000. A gas engine is designed to last about 150,000 before it needs an overhaul. Drive it longer and your looking at a rebuild. My last 4.3 had 286,000 miles on her before I totaled the truck. The '00 I DD has 175,000. My '93 got an engine swap at 190,000. The '87 with a 2putt8 got an engine swap also at 190,000.

If you drive it like you stole it youll get about as fall.