That rust is really common on the east coast here, most people just cut it out and patch it. Most Metuchen cars will have 2 stamped partial VINS on the apron, one is usually out of the rust area.
The 1 T seems like it should be a '71 Metuchen
That's common on early Metuchen cars and is pretty well documented. It's on waay too many cars to be a mistake and it's usually a 1,2, or 4 that precedes the plant code. I was told back in the 1980's by a Ford district service rep that it identified the assembly line but never had any way to confirm this but I'm sure it meant something to Ford. All states are different but the windshield VIN is the Federally recognized VIN on a 70 so a missing apron VIN shouldn't be the end of the world. There are several horror stories circulating regarding this VIN Anomaly, the most popular one is a 70 Boss that was confiscated in California ....
I've been documenting 70 CJ cars since the 1980's, since I'm in Pennsylvania, most of the cars I come across are Metuchen cars. Another thing I noticed is that Metuchen had the worst Quality control by far of the 3 plants .....
JMHO, John