Blue line plastic pump arm can wear or have hair line cracks. Green line wear pattern on steel s pin wear pattern. The s pin mloves in and out of pump shaft with up and down. movement. Check for burrs or smooth with file

Is there any place to get these plastic parts?

Looks like there out of service. Try walker next

https://www.ebay.com/itm/120345764441?h ... R5LYyYCZYg not the right one ,there were long and short yours is different. Thats carter number 111-120, you need carter 111-165 pump arm

https://www.carburetion.com/Products/Pr ... t=BBD-HV32 This looks right

Thanks so much! That site also has the other piece as well. Can you tell me if it’s the correct one as well?
https://www.carburetion.com/Products/Pr ... art=85-182

That looks good to me , walker number here better picture https://www.ebay.com/itm/120345763180?e ... R-jQuq2bYg carter number 111-118 for v8 but will work in slant models just a little more mid throttle lift of metering rod,good with todays fuel.

slantsix bbd most of time got this one,not as much metering rod lift at mid throttle, after market only services v8 model https://www.ebay.com/itm/403598194643?e ... R6TgoLSbYg

factory slant six green one https://www.ebay.com/itm/334859698709?_ ... %3A2047675

After market also came in black v8 type 111-118.https://www.ebay.com/p/2098143223