what is the difference between the actual mounts for the motor. not the brackets that they bolt to.

i know that one bracket is steel and the other is aluminum but whats the deal with the mounts. i bought 2 off ebay but they were exactly the same and smokin joe racing said they had to order one from mazda because mine were both from the passanger side.

anyone know if theyre interchangable or if the actual mouts are different here is a link to the auction i got

http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWN%3AIT

any and all help would be appreciated