Used LS Motor - How Many Miles Is Too Many?

[Winmon]

Thanks guys!

I wouldn't put a lot of value into the used ECM/wiring. You're probably going to have to send out your wiring harness to be reworkd or buy a new one ($500-$550), and you can pick up a new ECM with programming for $250 at the same time.

So if I go with a new LS3 along with a new engine control kit am I still going to need have it re-tuned? I am assuming the harness with it also still has to be modified? Chevy makes it sounds like it is plug and play. BTW, why would a new tune be required on a junkyard ECM? Is it to custom tailor it to my set up, i.e. trans, R/E gearing etc.?

i got greedy and boosted it up to 21 psi