I think you are confusing iron tailshaft for iron case. All of the ones I have are iron tailshaft, aluminum case. Not sure why they went that route myself.
If the OP is looking for a weak 5 speed to blow up behind a 440 consider an NP535/NV2500, at least the hack to make it fit will be minimal.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
