6 speed into 360 dart

Can't say from experience but, from what seems to be involved in putting in just about any trans that these cars didn't come from the factory with, I'd imagine a LOT OF HASSLE. You'll probably have to cut & reshape the floorpan & the cross member where the rear of the torsion bars attach. You'll also have to find a way to attach the trans to the engine. Don't know if it can bolt to any bell housing that attaches to the engines that are commonly found in A bodies or not. You'll need to figure out a clutch linkage, easiest way is most likely hydraulic.

Unless somebody is giving you a killer deal on the Viper trans it would probably be a lot less headache & maybe cheaper in the long run to use the new 5 speed overdrive trans from Passon Performance. It's a direct bolt-in replacement for what you have now.