here is a nice "late model" example with what I presume to be a 8v-71 and a single axle ( actually given the stated year (1979) i think it may be more likely to be the 4 stroke "fuel pincher" 8.5 or 8.2 I always forget because I heave never dealt with one )
a description and price are here
http://www.truckpaper.com/listingsde...x?OHID=4133625