Nissan Patrol 4x4 (Africa)

I know I have already asked for advice with this but one final bit of help would be much appreciated. I now have the EGT probe installed on my RD28 engine in the space where the EGR valve used to sit. However, on the bulkhead side of the now removed EGR valve there is a threaded pipe that formerly connected to a captive nut on the return pipe from the exhaust. Does anyone know the thread profile for this connection? Being a mechanical novice I was hoping this might be metric but it seems it might be NPT or BPT. I could cut off the threaded section from the EGR valve and fill it with weld to make a crude blanking nut to block the pipe from the exhaust but I would rather do the job neatly. I don't want to destroy the EGR valve if I can avoid it, since in this regulation obsessed country I might need to put it back at some point.

I don't have an array of thread gauges so can't determine this myself and the only outfit I have found who can make a suitable piece for me are 150 miles away. Has anyone else blocked off this pipe and if so how did you do it?

I am not up to speck with the uk shops ect but cant you just stop at a nut and bolt store and get the one that fits ?

Thanks Linus for taking the time to reply. That is what I will do, though finding a shop that carries a useful range of bolts has taken some time. The reason I put up the post is that I want to ensure that since this is where the exhaust gas is drawn into the EGR valve that the seal is a good one. That's why I wondered if it was a tapered thread. Also, I don't want to damage the thread on the existing captive nut by forcing an "almost feels right" bolt into it. I don't like doing procedures that aren't reversible if they don't work out. Just me being fussy really.

Ok l misunderstood you the egt probe is 3/8 gas you must look for pneutics suppier in your area if the egt probe went in there the pipe must be the same thread it is tapered . Some of the smaller sizes NPT and BSP are the same hope this helps Pieter c says you must send him pm if you dont find one he knows of a few in the uk

Tinus that's really helpful - thanks a lot. Hope to have it all sorted by Tuesday. Will keep you posted.

Transnamib, I don't quite understand where you have installed that EGT probe. Can you post a pic of the installation.

Why I ask is because the EGR usually runs around the rear of the engine and that would only maybe cover the outlet gasses from the last cylinder. When measuring EGT you want to pick up on all the cylinders. If you have a turbo, place it between the outlet manifold and the turbo as close as possible to where all the cylinders come together.