Sure are. I have a small-block 727 push-button tranny in my shed. I paid $100 at a Mopar swap meet, incl torque conv & adapter to change from B&T to a sliding-yoke driveshaft. A few months before that a guy was selling one on craigslist, also $100. For an early-A, you need to beat a flange in the tranny tunnel flat to fit it, but otherwise supposedly bolts-in. Mine is 2000 mi from the OP and not for sale, but shows they are available.