I know many of the diffs but lookin at a block how can you tell a 87 to a 89. I got sent a 89 j-spec block for my 87 turbo II, They told me they switch the front cover and put a 87 on it but i just what to make sure there tellin me the truth

 

The key difference on the front cover is that the 87 use a mechanical oil metering pump while the 89 and newer use an electric one, so performing the swap is necessary.

 

use the 89 turbo and exhaust manifold!! by changing the front cover to the 87-88 one letsyou run the mech. oil metering pump as mentioned above. if you don't do this you will need to run premix as the 89-91 pump won't work.