Factory is a eight blade pump A/C 340 also got a eight blade but more often and not ended up with a 6 blade when changed over the years. Try to keep to the eight blade one on the 340 high comp as they cool that engine better the 6 is fine on the low comp one. I know it should be the other way around but I have had 340s and 360s for 40 years and this is what I have run into with them