Coinsandcanada.com

Hi, I am new to this board. I have some $50 banknotes I am trying to evaluate. I will take some pics and post later but in the meantime I need a little help in identifying prefixes. The ones I have seen discussed are 2 letter ones. Mine are all 3 letters. EHE, EHC, EHF. Do you only look at the last 2 letters? Advice much appreciated.
Thanks

It would help if you stated what year the bills are and what the signature is.
If you are referring to the 1975 issue, they were issued with both two and three letter prefixes.

Yes they are all 1975 Lawson Bouey. Thanks