I was reading the thread about the 09 mufflers when welding of the muffler shells was mentioned. Was anything on a Model T welded? A lot of rivets and solder but I can't think of anything welded. It seems like the left front body panel (with the dummy door) was spot welded to the quarter panel on my 14 runabout. At least that's how I put the 2 together when I replaced the front section, but nothing arc welded comes to mind.
Horn wire tube is spot welded on.
Many parts were welded. Ford Methods and the Ford Shops (1914) note with photos the spot welding on the mud guards (fenders), the front fender apron gusset is spot welded. The 'fender ribbon, the fender peak, and the fender apron are electrically welded.'
Contact studs in the commutator were electric welded.
A lot of forged assemblies were flame brazed or spot brazed too.
Wire wheels on '26 and '27 cars were welded and I believe the process used was a rather unique one.
I drive a lot of trails and dirt roads, as a result I have suffered many muffler troubles.
Now when I buy a new muffler I torch braze all of the seams completely "but not the muffler to the pipe" with a soft flame (not to crystalize the metal).
Results are a great sound and no vibration fatigue.
I have seen spot welds inside the Ford coil box lids to keep the inner shelf in place. The tabs are great to locate but not enough to keep the shelf in. I don't know when they started spot welding them but I have seen the early lid missing the shelf, for lack of them.
The transmission input shaft is welded to its flange.
If the brass splattered all over it counts as welding, you have to include the oil pan.
I always put few spot welds on each end of the after market mufflers. They do tend to fall apart when driving or when the car backfires. A few spot welds will assure that your muffler stays together.