Which model years of 140 mph speedometers are a direct replacement for my stock 85 mph speedometer? I have a 1986 IROC Z-28 with automatic and 305. I do not want to get too in depth, just thought if any model years would bolt right in, I would do that. Any help is appreciated.

 

You will need one that is cable driven which on camaros ended in 1989 as they went to the electronic or VSS type in 1990. So any camaro speedo from 82-89 is a direct bolt in. However, I believe that the 140 or 145 speedo became available in 1986 so that limits you from 86-89 model years.
Good Luck!