Whole house surge protection

Pete, is this what you have?

I purchased mine as new old stock; so it was relatively inexpensive (less than $500). My case though was sealed with no conduit openings. I did have to drill a hole into the case for the 3/4"/1" short metal conduit; which was actually most difficult; having to buy a special metal drill bit. It only added maybe 2" of wire to the fuse panel. Ideally though you want to attach these style surge protector right to the side of the panel keeping the wires as short as possible.
The Leviton 51120 that video321 said he installed is a nice unit but I decided to go with the best which is the Leviton 52120-M2 with 100,000A protection and replaceable modules with a lifetime guarantee. You can find the best prices by looking at Google Shopping and Amazon.com. I have more information about these at http://www.nicewire.com/article/whole-house-surge-protectors/ and http://www.philsbest.com/home-improvement/best-whole-house-surge-protector/