98 grandprix engine swap 3100 to 3800

[TheBlackReaper]

hi guys i was wondering could anyone help me with a few questions i have about this swap. i already have the engine, im currently rebuilding it. my dilemma is my aunt has a 03 bonniville who's 3800 is knocking like a jehova's witness and she wants to trade engine's (3800 to 3100) out of my car for her tranny which would be nice, i.e FREE parts!!!! any suggestions or info would be greatly apreciated.

[FordMan77]

Yea, find a good low mileage used 3800 and swap that into the 03 Bonne and call it a day. I can't imagine why you'd go through the trouble of switching from a 3800 to the 3100. These motors can be had for 4-500 all day long. Reuse all your components.

I would think this would be a major electrical PITA to make work. Not sure the harness for the 3100 even comes close to working w/ the 3800. Then you have to swap ECM's, etc... I'd just keep both cars stock and go. No fuss, no muss.

I'm confused, lol... So basically you are going to remove the bad 3800 from the bonneville, take her trans as well and in exchange give her the 3100 from your car (that you are rebuilding). So you then have a knocking 3800 with a good trans to but in your car, and she has a rebuilt 3100 and NO trans to put in the 03 Bonne?