Which is better?

I couldn't find much info on the difference, and the only thing I could find said that the cast iron is more heavy duty and last longer. Mines leaking from the back, so I need to replace it soon.

 

not that it matters very much, but what vehicle is it for?

 

91 Toyota pickup 22re. I had a couple of beers and order the aluminium one off ebay for $85 shipped.

Going to have to rig something up because I don't have a bench and I don't have a vice.