can a gen 4 ecu be made to run a gen 3 engine?

[greaserturbo]

Hello,
Customer brought me a 07 silverado needing engine/trans replacement. 4l60 4wd square port AL 6.0 equipped, he bought replacement engine/trans 4l80 cathedral port iron 6.0 from an 02 and he's asking if the 07 ecu can be made to run the replacement engine.

Thanks all!

[blindsquirrel]

If it's an '07 Silverado Classic with a P59, yes. If '07 Silverado with E38, nope, not unless you pull the crankshaft and change the reluctor wheel.

[ehall8702]

Learned the hard way about this same issue, at least crank isn't hard to pull and swap the $35 reluctor wheel, crank sensor,$35 4x cam gear, and drill and tap new holes on block bungs for gen 4 knock sensors, had to clearence passenger motor mount tho to not hit knock sensor. I believe there is a adapter harness from gen 4 to gen 3 knock sensor but don't quote me. Good time to add a oil pickup tube bracket ( two bolts vs one bolt hold down) also. Was told I needed a jig to place reluctor wheel properly, but I made a video how I did it, worked great zero timing issues.