Eshoppes PF-800 bulkhead 1 5/8" .... ?

[D3DPrintedThingz]

So I brought the bulkhead connector from the Eshoppes 800 gph overflow drain. I tried the 1, 1 1/2, 1 3/4, 2 inch female threaded connectors. They did not connect. I brought it home and measured it, angrily, and it seems to measure at 1 5/8". Is it actually a mm measurement?

How do I connect the rest of the PVC and various tubing to this unscrewable fitting?

P.S. I am not a plumber, but I do have the crack of the bum, so don't use big words or I'll just have to pretend like I understand...

 

[KrisReef]

Bulkhead threads in my experience are randomly applied to the extent that if you don’t get the same batch number from the proprietary supplier that they almost never can be matched except by a machinist who can cut a replacement, generally at exorbitant costs for the part.

without belaboring the point, I have found that it is simpler to measure the existing hole and access dimensions and purchasing all the fittings from your local pipe store