Fuel tank sender unit differences

[multisi]

There are 2 standard fuel tank senders,one early pre 86 and later post 86, what would the differences be , would the dash reading be out if the wrong one was fitted. I have an early new genuine unit but havnt fitted it.

[Aidan]

doesn't appear to be any reason for the difference as the circuit board and the gauge didn't change, neither does the tank or seal or plug, I'm guessing it was a manufacturer change, there was a suffix D as well no idea what that was for; you can test it before putting the tank back