Those IBT ones are hot. Anyone know a good date for em?
IBT series 18850-18999 built by Trenton Works, Sep-Oct 2000.
I like the IC Death Star boxcar, but I believe that these cars are too late for those of us who model the early- to mid-1980s. 
DFF
IC series 533000-533099 built by Gunderson, Lot 20065, Aug-96
I think the Grey IC with the deathstar logo is way past your era aswell... might even be into the 1990's...