I bought this pump used, it is from a 4bt with an A pump. I took it apart and it has the bushing/small piston and the conical spring. You think it would be OK to run? I know it is not one of the common low pressure pump part #s, but seeing as how it has the right parts inside, what do you think?

 

Feel like taking apart the one in your 84 d150? If it's the correct pump, you could compare each pumps springs.

 

Bill, I had to rob the one from the 84 to put on the work truck, as its diaphram pump finally bit the dust. I picked up this used one hoping to go to the dragstrip again this year.

 

I did a bunch of pump research here:

https://www.dieseltruckresource.com/...d.php?t=183104

 

You never did report back with output pressures..