it works. the car does go backwards and there is no lag when it engages reverse. i'll fiddle with it a bit more to see if i can dial it in better.
thanks for all the help.
john
p.s. i took a quick look on craigslist
http://sfbay.craigslist.org/eby/cto/1053605228.html
http://sfbay.craigslist.org/nby/cto/1052088849.html