upper engine mount

This afternoon I left the hospital early to attempt the band adjustment on my transmission. After the neighborhood girls started riding by on their bikes pointing and laughing about the man lying on his engine, I decided that there must be an easier way. To aid in visualization of the adjusting bolt I disconnected the vacuum lines and air cleaner plumbing from the twin throttle boddies. Not only did this allow adequate access to the band adjuster, it also shed some light onto the strange clunking that I’ve been mistakenly attributing to my slipping transmission. The dog bone shaped mount that connects between the firewall and the engine/transmission housing had sheared into two separate pieces. I assume that this happed when the transmission was replaced before I bought this car. I really don’t know. Has this ever broken on any of you? Is it an URGENT matter to attend to or can I put it off until next week? How much does this little plastic wonder cost? Thanks for your input!