I can’t speak to the "No-Drain-Plug issue, but in 1983, I had a 1973 Pinto Station Wagon, V6, 2300cc, 4-speed, and it was a really nice car, ran well, was comfortable and in spite of its age, it was in really nice shape. I had just noticed that the rear end, at the input shaft, was leaking a bit and the house we rented at the time had a garage with a dirt/gravel floor, so I had no idea how long it had been leaking.
I tried to loosen the fill plug so I could top it off, but it was not coming loose, even with a “goodly” amount of force, I was not going to go to extremes and risk stripping that plug apart as it was not solid steel, but rather a pressed design welded into the treaded ring that screwed into housing fill hole.
I finally took it to a couple of dealerships, first a Ford dealership and then finally to a Mercury Dealership…
And that is where the story takes an awful twist… The mechanic they put on it decided to try a “little heat” and broke out the acetylene gas torch and he stated heating the case around the filler plug and put a breaker bar into the plug…
What he did not do was drain the housing nor consider what the heat would do to the oil in the housing, but he found out, the fumes from the superheated oil exploded and ruptured the back of the housing. When I went in to see the car the next day, the mechanic was still in the hospital with flash burns to his face, hands, and arms (He did make a full recovery…).
The dealership said they would make full repair at no charge, and I guess just to be funny, they also offered to make a good deal on a new car if I wanted…
I think I surprised them when I said, “Oh yeah, what type of good deal?”
When all was said and done, I bought a new 1983 Mercury Lynx LS with the High Performance Sport Package. Now, that was a fun car to Zip around in…
As for the Pinto Wagon, they gave me High Blue Book Value as a trade-in, and I got the Lynx for its Base Price, all the factory addons were free as well as the dealer added extras: window engraving, undercoating, floor mats, inside and outside protections package (extra wax and scotchguard), and more…
I really liked that little lynx, but that sport package included metric high-performance Michelin Tires on it that barely got 20,000 miles out of a set out of the tires (really good road handling…) and back then only Michelin Tires fit those alloy rims… I kept that car for about 10-years or so…