he is talking about the rubber inspection cover. you usually need this to install/uninstall the driveplate on automatic JZ engines. It installs on the lower portion of the upper pan to the rear allowing access to the driveplate or flywheel as i have described. my front sump and rear sump pans came with one i can prolly take a picture in a bit here....
edit :
The 7m's is sitting on my 2jz automatic right there its bigger than your average jz one.
not sure the part# you need... there is no stiffner plates for the jz's. the part that bolts to the bellhousing was designed to be thicker.... i did a comparison actually in my build thread between the m and jz.
if it is the inspection cover
3110114010 and 3110214010
170$ each from a local dealer or 68-70$ online at toyotapartscheap.com or champions or others~