[ImperialCrown]

Welcome to Allpar. Are you talking about replacing the intake manifold or just the EGR plumbing? They may be metric or standard pipe thread.
Removing the manifold from the car may allow a machine shop to drill and re-tap the hole. Any K-car or 4-cyl minivan may have the same pieces.
You may still be able to replace the EGR tube.
Is it like this?: 31-139 EGR Tube.jpg
Or this?: getimage.php

 

[ImperialCrown]

The fittings are pressed into the throttle body. It may be a standard 1/8 " steel tubing with a bubble flare at one end to hold the hose on. Maybe drill out and tap in a scrap piece of brake tubing?
I can only think that the fitting 'rust off' was caused by condensation and exhaust byproduct acids being sucked in from a leaking EGR valve. Exhaust gases contain a lot of water. You might want to check and replace the EGR valve.