...triangular hole pattern? Could be Conoco...if you measure the distance between the holes and their relative angle to each other, it should give you something to compare to the hole pattern on a Conoco pump plate...and I'm pretty sure Oklahoma was in Conoco's marketing territory...I don't have one, but here are a couple of photos of possible suspects, from a Google search...surely someone on Oldgas has a plate, and can confirm the distance between the mounting holes...
...Joe (jkyocom on Oldgas) does nice work...as far as I know, he is still restoring computers...his email is listed under his User Profile...
Here some pictures of the screw holes, it's not 3 in a triangle, it's actually 6 holes.
