Brake Master Cylinder leaking problem.

Definitely your problem, the rebuilders get them in and just clean the lids up after being banged around in big bins.

The local parts stores usually only have the lids for the Chebby's. Check with your local junk yard, that style cover was used up into the late 80's on pickups and cars at least to the mid years. I don't have any spares right now or I'd send you one. A last resort the dealer should have or be able to get you one. Check the dealer clunker stock piles on the back lot for a PU or Ramcharger, you can probably talk them out of one.