Jerry raised a very important issue..... Unless you have a way to machine an adapter with that shape, there won't be any flange for the bulb to tighten against.
The original early 216 engine the sender has that special flange that no regular adapter will allow you to seal the sending bulb. The early flanged senders are easily recognized by the four sided bolt top...... our solution when working on the 261 is to buy the cheap aftermarket temp. gauge JUST to get one of the adapters in the kit .
Caution: if you over tighten the adapter into the head.... the head can crack........ so far the JB Weld on the thread is holding and has been for a few years.
We have a further complication...... the early military 216 trucks had a steam line connected in that hole and vented just under the radiator cap. It was meant to release air pockets that may have formed inside the 216 heads during very steep descent or climbing. I means having a T fitting with a line to the radiator and the heat sender bulb fitted to the top of the brass t fitting. We first tested them in operation using a clear nylon line and where amazed at the froth that was sent to the radiator....after some time in level position it becomes clear green antifreeze. At that point, the temp line was replaced by a solid steel brake line to the rad.
Bob C
Can't remember how to attach a picture!!!!
