if Bernie's stuff is not the same as yours..... as i recall, the stock hole and fitting are 1/4". some gauge senders are the same, but a lot seem to be 1/8".
my new elec sender was 1/8...so i use a1/4", 1.5 or 2" extension from the hardware store. this screwed into where the stock sender went.the other end went into a 1/4 tee. the stock sender went into one side of the tee. the new sender (1/8) went into a 1/8 to 1/4 adapter, then into the tee. packaging was tight.
another option is to remove the hex tube deal that the stock sender screws into, and tap this for the new sender. tap it so there is room between the stock sender and block (works much better for mechanical gauge hook up, as elec senders can be bulky).
you can get all this at the hardware store for a couple bucks.
hopefully your is as easy as Bernie's was. but in case its not, and was like mine.....