Ran across your thread here on a Google search... If you guys are truly looking for a 58 Suburban for a build, you might be interested in this one
58 GMC Suburban 4 x 4
This unit is all original, less than 10,000 actual miles, in running order!
Lannon Fire Department acquired it in 1966, it was a Civil Defense Vehicle prior to that. It is still in service at the present time, it is still responding to brush fires whenever they occur, but it will be retired shortly and is going on the auction block. Proceeds will go to the department's equipment replacement fund.
Contact info on the page there, should you have any questions on it guys!