Airhead Rear Main Seal
I have the rear main installation tool jtwind sells. In the instructions he mentions two different depths for the seal to be installed to. It is differentiated by whether or not the block is machined in the area of the main seal.
I just installed a new seal on a 76 R90 and used the deeper setting because when I tried the setting for a block that has not been machined, the seal rubbed on the flywheel.
What were the year breaks for the later and earlier seal depths? Does anyone have pictures of both? Jtwind?