85 Carbed 300 converted to DS II and non-electronic carb. Been running great for years.

Problem - The EGR tube comming out of the front of the plate going to the air pump rotted apart. So I'm looking to take out the old tube and put a plug in the plate. Need to find out the size and thread type. Found a post where somebody guessed it as an M20. Antbody do this ???

 

Mine did the same thing right before the 1bbl carb got replaced, EGR pipe rusted off right at the end of the valve in front of the carb mounting plate. I plugged the hole with a cast iron pipe plug, believe it was 1" NPT. Honestly I'd save the trouble of trying to extract the old rusted to heck fitting and just jam a 3/4" plug into the remains of the old pipe. Would be best to do this off the vehicle as you don't want rust scale going into the manifold.

 

Got to take it out. It rotted off between the tube and the check valve. Hot exhaust comes out of it. There is no place to insert a 3/4 " plug. The tube started to crush when I tried to get hold of it so it would only be a temp fix if you meant stuff something in it. It's really tight. Got penitrating oil on it now. May be a beahhtch to get it out.