i am trying to find a affordable used prop locally and i cant decipher the numbers mine currently is a 14.25x21 on my merc 165. im looking at one the guy says the only numbers are 48 832332 415 21P. i cant find any info on it
You don't say if you're happy with the performance you're getting with your existing 21"p prop. If you're happy with it, the the prop you are looking at, with a part number that ends in 21p, should give you similar performance - IF - it fits.
How old is the old prop? Mercury made some changes to there prop lines in the late 70s, the thrust washers and the hardware at the propnut end differs between the older and newer.