Correct Fuel Tank Sender For A 70 RR with a 383

[soundhd]

Need to replace the fuel tank sender in my 70 RR. Has a 383. Went on line to look for them and the are listed as 3/8" or 5/16". Which one is the right one for a 383?

 

[BIGSHCLUNK]

3/8 is HEMI, 5/16 would be stock on a 383 TMK

 

[soundhd]

Thanks guys............