Looking for thread on modifying 67-72 temp sender

[BigRed76]

I saw a thread a while back about taking an OEM temp sender for 67-72's and milling it down to 12x1.5 threads to fit into the cyl. head of an LS. I tried milling down an OEM 67-72 temp sender but there isn't enough material to get it down small enough for 12x1.5 threads. I've spent hours trying to find that thread and have been unsuccessful, so I'm curious has anyone else successfully done this? Is there another OEM GM temp sender that it smaller and can be milled down for 12x1.5 threads? I've tried some aftermarket temp senders and they don't work, and drilling & tapping the head isn't an option since the engine is in the truck.