I have a Gear Vendors unit. As far as I know, it is the only thing out there that will bolt up to an sm420. It is worth every penny. I get to keep my granny gear and 3:90 posi, and can overdrive 2nd, 3rd and 4th. The split between 3rd and 4th is exactly what our trannys need. 4th over is more cake and icing. I can go 75 at 2500 rpm and can have a conversation or listen to the stock radio. It is good for a working/towing set up and when used in that manner it is much stronger and will outlast any s-10/camaro 5 speed. GearVendors.com
