What is the best way to get an overdrive auto in a 67 Barracuda?
I'd skip Monster trans. Their transmissions are only rated to handle a touch over stock, 350 hp. Skip the Wilcap adapters too. They are a primitive way to adapt the 200R4. Gear Vendors is like a bandaid overdrive. Too little of an overdrive ratio for too much $. If you are going to do it right, it's going to cost you. I find real .67 overdrive is worth every penny.
I put a 200R4 in my '68 A-Body. It's the best automatic transmission I've ever driven, and one of the best upgrades I've done on my car. I have 3.91's and 28" rear tires. The car launches visiously and can cruise all day at 2500 rpm at 80 mph.
There is a kit from US Cartool available to install them now. You will have to alter the torsion bar crossmember, but not the floor. I used a Reid bellhousing to adapt mine to my Magnum.
I used a 3600 rpm stall converter with the 3 carbon fiber clutch pack from Precision of New Hampton. It makes the transmission feel like a 5 speed automatic. It's awesome.
The bell housings are available to adapt the 200R4 to Small Blocks, Big Blocks, Hemi's and Gen3's. They can be built to hold 750 to over 1000 hp. Lenny at Extreme Automatics is the man to talk to.