are you going to run a river screen?      Son just found out how obsolete his  B3J  (13 inch impeller)  was for  replacement parts, namely the impeller.  You want to protect that or any pump  the  best you can! 

So, instead of  buying a   extremely high priced and  NOS  impeller,   he bought  a  complete  B3Z   pump for just  a few bucks more than what they wanted for just the   impeller/shaft/seal  kit..     


Looks like  years of   pumping a little sand  got the  fins  buzzed down pretty thin-  To Be Fair,  that pump was used when installed 30 yrs ago..

then  when a  screen cleaning nozzle  broke off and inhaled it  broke a couple  fins off--   meaning the  screen system  did it's job,  but ultimately  killed it in the end!!      screwed if you do,  screwed if you don't.   LOL.  


His is  SAE  direct engine mount,   so I can't say how many belts you'll need-    4  seems  common.      According to  NACP (Rockford clutch)   they can take  'normal'  type side loads,   as long as you don't over-do  the static belt tension.      So don't  try to overcome  slippage with increased belt tension---  get additional belts!