Got my new sender. I ran a boring bar through the autometer adapter fitting, and was able to get the sender to fit through it OK without touching the sidewalls. Its really hard to do with a twist drill unless you have the correct letter sized drillbits, and have a way to perfectly center the drill to the existing hole. Even with my mill, using the table, it was tough. I could have chucked the drillbit in the lathe's tailstock, but the boring bar let me step the hole size up slowly until it was just big enough. Screwed into the engine, and all set.
Also got a new seal kit today for the dana 300, and a new defroster duct, and a trans temp gauge. I need to read up on the best spot for the trans temp sender.