Transmission update for an a-727

I was noodling through speed channel the other day and a show called search and restore was working on a Hudson with an a-727 trans..I missed some of it but they said they were installing a bolt on unit to the back of the trans to increase gas millage (but nit hurt performance) but over 20%.

I have done some searching but I cannot find it.

Anybody have any info on this and I hope it isn't really $$$$$

Thanks
Ian.