The gold standard for stock replacements is to go with E46 Convertible/M3 Mounts (Part# 33-52-6-754-096) combined with a Z3 mounting plate (Part# 51-71-8-413-359). Order off the part number as not all E46 mounts are the same, and the part listed was a BMW redesign to deal with chronic failure of rear mounts. The mounting plate is also a good idea, especially in older cars, as it is designed to prevent sheet metal from ripping by spreading out the load of the two mounting bolts. Just google the part # and a Pelican Parts tech article should come up.