The 3800s have the 60* bellhousing and are mated to a T5. You could adapt a 6 speed but you'd probably need 4.56-4.88 gears in the rear to be able to pull 6th gear. I think the 3800 swap with/without supercharger would be a better swap than a 4.3. Sure, you'll be down on power compared to the 350, but at least it will actually get you some mpg gain. I've been told by guys who had the Camaro/Firebird with 3.8 that they will get high 20's if you have a light foot and keep it under 65mph. They are quite a bit more aerodynamic than a Gbody though.dream on mcss said:BUT, if you could get this to work, you'd be able to put the six speed in the 4th gens behind it.
The 3.6 timing chain issues are well documented. They are causing major fits in the dealership by setting random misfire codes that can't be "tuned away". I wouldn't consider it a viable swap option due to cost more than anything. Expensive to buy, expensive to install, expensive to tune. They are an impressive motor on paper. So is Ford's Ecoboost turbo V6. I think time will tell whether either will have any real lifespan. Any time you try to squeeze out a bunch of power from small displacement you can expect more trouble.