93 thru 95 red engines have an F cast into the block near the rear freeze plugs. It will have a knock sensor port on the trunk side of the block, midway. It will have starter mounting holes on the trunk side starter boss ar the bell housing. The starter as mounted in the Fiero will not be fully supported on the forward mounting bolt flange.
I don't know the casting ID for the red 3400 but it should also have the knock sensor port and the starter will be fully supported at both mounting bolts. No starter mount holes on the trunk side.
Check the newsletters for the engine listings previously published for 3400 rwd ID casting.
