[mitchntx]

Glenn has done tons of research on this and we are both about to the point of have custom machining done.

Autometer guages have a sending unit that is 1/8" NPT.
An LS1 motor has ports machined in, but are 12x1.5 metric.

Sure there are adaptors, but the wall is so thin the adaptors twist off with MINIMAL torque. And by that, not enough to crush a seal enough to prevent a leak.

Why don't they make a 12x1.5 sender?????

The stock sender ohms out WAY different ... almost 1K ohms lower than the AM.

[GlennCMC70]

o.k.- sorry, i wasnt clear. i have had this part in my car. the 2nd time i installed it, it broke into the head. it wasnt made by autometer as they (autometer) only make a M12x1 (not 1.5) and will not work. also, the hole though the adapter must be large enough for the tip of the sender to exstend through (about 5/16" diameter) so no matter the manufacture, a M12x1.5 threaded part w/ a 5/16" hole in it will only have .030" thickness from the valley of the threads to the inner wall of the part. i even looked into having a local machine shop take a M12x1.5 male that had a -4AN male on the other end that was made of steel. told them to mill off the -4AN side, drill out the fitting to accept the tip of the sender and tap it 1/8 NPT. i told them i knew it was gonna be thin and don't worry about destroying it in the attemp to made it, that i was willing to accept the loss of a $10 adapter plus the machine shop bill. they called me back and said that they were so sure it was gonna break that they wouldnt do it or take my money to try it.

as mitch said, i've done the leg work on trying to make these senders work w/ existing holes.
by the way, that temp sender is a 12mm socket size. thats the perfect size to make a M12x1.5 sender from. 1/8" NPT is like only a 64th of an inch smaller.