Here is the correct phone number for Rich @ Midwest Power Products,
815-942-0550
http://midwestbooster.com/One digit off willy.
I had a nice chat with Rich and he is going to help my friend get the correct stuff for his truck. He was telling me that the later Chevrolet trucks don't use the same hydrovac that the earlier trucks use. They have 2 different systems that are used. One type has a 13" vacuum booster that mounts to the firewall with the master cylinder mounting to it. The other type system uses power from the power steering pump.
Don
