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Pulled a 215 Buick from my 78 Sunbird wagon and am installing an 84 3.8 Buick which is a 215 minus the front 2 cylinders supposedly. Bottom half of motor mount was left in place and am hoping the new top halves from rock auto will be correct and bolt into place . Also ordered a flywheel from them for a 79 buick century 3.8 which was the closest application I could find a flywheel for there. Examined the 84 flexplate and the flywheel and find they both appear to have weight reduction in similar locations. Will take to machine shop to see if they are weighted the same. Just thinking I might be able to rig my own setup with a disk a string and a reference weight standard set. Suspend horizontally and see if both dip the same degree with respect to the alignment hole and if both can be leveled by dropping the same weight on top in the same location. I know V6 balance is supposed to be tricky ... I think that would tell me if I should give this a try. I think the machine shop charges 200$ to modify.

Looking at some headers for the v6 and wondered about fit. I found a set of banged up Gebler stepped headers which were expensive headers when new, these appear to be tuned and appeal to me more than the Hedman offering which is the only other I find. Wondered if anyone here might know of the tight spots doing 3.8 in an H-body ... actually it looked pretty roomy around the v8 when it was in there. I think the biggest problem would be if they are too low when they go horizontal to collector. Really they dont look any lower than the Hedman.

Some of the Monza wagons came with a 3.8 in them. I don't know the differences in the wiring harnesses from the 215 to the 3.8 but finding a factory harness from a wagon with a 3.8 is possible. It's been about 10 years since I did the 2.5 to the 3.8 swap in my old 77 astre wagon. It not too hard of a swap. Just get the car high enough off the ground if your putting the engine in with the tranny attached. That's where I had issues. As for headers I have a feeling those won't work in a h body. I've never heard of anyone using them. And I don't believe anyone is currently producing a set that will work with the 3.8 in an h body.
If I remember correctly the mounts and plates from the 3.8 have been used to install 215's in h bodies so hopefully the reverse will also work. Someone else will have to speak up about the differences between the original 3.8 h body mounts and the later 1984 mounts though.

Looking at your swap being an 84 eng. and your q about headers got me to pull out an old book by John Thawley produced in 1980 about swaps of v6's into Vegas. He stated that the factory exhaust is good for a daily driver and "lightly modified" engines.This would make for an easier install and exhaust system (duals) If you want more flow,You could send them to a company called "Extrude hone" that can increase the inside of the manifold for better flow. They have a price list of operations,if you want to go that route. Also you might want to check some Jeep websites as jeep used the v6 back in the 60's or 70's and there is lots of info on the v6. Just some stuff you might use to make your swap easier. Oh yeah, there is always e-bay and Racing junk to check out. for eng. mounts check out Bob Gumms (?) site,lots of good stuff there too.

Hooker also made a nice set of Buick V-6 headers for even and odd fire engines for Vega's. I only have the #202 in my notes I assume they are for the even fire engines as that is what I have in my 78 Sunbird wagon. They fit very well. But they have not made them for about 20 years.

I know V6 balance is supposed to be tricky ...

Back in the day factory fresh 3.8 would have a little vibration. It was all a crap shoot because GM just figured it is what it is which is a V8 missing two cylinders. That said a good reputable machine shop can balance the motor, just be sure you have the correct harmonic balancer, flex plate and crank as well as matched rods and pistons. If done correctly you will have zero vibration or at least undetectable in the 12-1600 rpm range where it is most noticeable.

I've never been able to get either of my 3.8s to stop shaking & vibrating. Odd fire & even fire - didn't matter. I have driven one other that was a bit smoother than mine.

Hey OldsStarfire, how does the vibration compare to the before you did the rebuild with the 3.0L pistons. I'm using 3.0L pistons too and the vibration is pretty bad between the 1200-1600 RPM range listed above. It feels like a vibrating bed in the 30-45 MPH range. Feels ok at 65 but it's turning 3K with the 3.23 gears . Man this needs a fourth trans gear. Unfortunately I didn't get to drive mine more than a few miles before the engine swap because it was knocking when I got it. I just fired this thing up again after having been sitting for the last 6 years and had forgotten about a few things when I parked it.

I suspect that the 3.0 pistons that raised the compression made the shaking worse because of the raised compression and more horsepower. Stock engines seem smoother to me but its not very scientific.