Early A Speedo Pinion

Well my original 21 tooth Speedo pinion is finally beginning to give up and with Layson’s turmoil its doubtful they will reproduce one anytime soon, I guess I need to consider alternatives. I understand there is a device that will adapt a new style pinion but was a little unsure what it look like. The access room between the transmission mount and the hole for the pinion in my 4 speed car is very limited. Is anyone familiar with the device and will one fit without altering my transmission mount.