Im not sure why this is such a big secret, I cant find what Transmission I have it has trans code A and I cant find anything on this. Thought I was making headway when someone said it was a New Process 435 but research lead me to find out the 435 was used pre 1985 so back to searching endlessly. So frustrated any help would be greatly appreciated thanks. Im including a pic of the door sticker.

 

Well if you can't find anything online and d'ont have the owners manual, Try looking under the truck at the trans itself.
But like you said, everything Ive found points to an np43.

 

I came up with a New Process Model 435 too. But it comes up as a 1986 transmission. I think you were involved in a model year transmission change. Do like Shagg said, try to find the number on your transmission

 

Post pics of the transmission.

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