We offer a year warranty on our units even for racing use.
However I wouldn't be sucked into the warranty as much as the reputation of the builder. A warranty is worthless if you have to use it all the time.
We back our products and most good vendors do, even sometimes when it's out of warranty or an installer error.
We aren't doing 4L60E's yet for shipping, only local customers but I'm sure that one of the other vendors here can fix you up or refer you to a good local builder maybe.