I bought these alloy engine / gearbox mounting plates off ebay about 7-8 years ago. I have no idea who made them but being right and left sides with rounded edges makes me think they are not one off parts and most likely production items from an aftermarket company. Anyone recognize? They are 1/16" thicker than the stock steel plates and a lot lighter.
All of the drilled holes are right where they should be, except for the top gearbox mounting slot.
So a stock plate was bolted up and slots were marked and center punched.
Holes drilled and next the slots were cut with a jig saw.
Due to the plates being thicker than stock the bottom two mounting points needed to be milled down. Down the street at my Dad's garage his low buck garage milling machine was put to use.
Next came some polishing and hand detailing and presto, custom alloy engine / gearbox plates.