A little late here on the post, but I was searching for the same thing. I want to install a Keisler 4-speed system in my Demon. As of Sept 1, 2011 the 550 lb unit is $4599.00 plus $200.00 to ship and requires a little modification. But I can not find out if the floor tunnel has to be cut as it does with a 727 to 518 and/or the gear-vendors kit does require cutting.
And then what are the end results. I read people saying in the B body it' OK....but the question here is A body.