replacing timing chain?

[ranmar1]

Just received a 1996 Explorer with 170,000 miles. Owner said it just quit running and his mechanic told him it needs timing chain replaced for $2900. It's in great condition other than that. He just went a bought a New one. How difficult is it to do this repair? I can't afford to let the shop do it and it's way to nice to junk.
Appreciate any advice or how to info. Thanks

 

[ranmar1]

Correction, it's a 1007 4.0 SOHC. turns over doesn't sound like it's trying to start.
Is this a internal damage engine? if its out of time.