Looking at prices, they aren't that much cheaper than ATK which I have sold without issues, and have a great warranty they seem to stand behind.
-2001 Tahoe original 5.3 4x4 only 430k
-A Metric Butt ton of three wheelers
-1985 V65 Magna
-1983 Nighthawk 650
-1969 F250 Highboy built 360