Hey 3B, hope your staying warm.
The tank I was looking at on Rock Auto uses a sending until that has a lock ring......the tank I looked at Tank Inc. has one that the sending unit has the five holes with the two holes off set that you mention.
I'll check the one in my original 37 tank and see if the holes match.....the other "problem" may be that the mustang tank sits in the tank at about a 45 degree angle where mine is flat. However that does not mean I can't make it work though!!
More later.
