Need info on '71 Merc 500-9 lower unit replacement

[MartyTn]

Help appreciated from anyone with a Merc Where-Used book - or other knowledge - that covers 1971–1974 lower units. I have a ’71 Merc 500-9 with lower unit P/N 1626-3927A. I need to know if a ’74 Merc 402 lower unit P/N 1643-4930 is a workable replacement for the 1626-3927A. My where-used book dated 1971 shows the 500-9 and 402 using the same lower unit for ’71. Thanks, Marty

 

[NathanY]

Re: Need info on '71 Merc 500-9 lower unit replacement

Dont know what the 500-9 means, but if you have a 50hp 4 cylinder, and you want to put a lower unit off of a 40hp 2 cylinder, I dont think it will work. You will need a lower unit off of a 4 cylinder, like the old 65hp, or any other 4 cylinder that uses the smaller l/u.

 

[MartyTn]

Re: Need info on '71 Merc 500-9 lower unit replacement

The 500-9 is a specific model of Merc 500 as used in Merc internal where-used info. It is still the 4-cyl 44ci engine. The 500-9 and 402 (40hp 2 cyl) did use the same lu in '71. I'm looking for specific info on whether these two part #'s are interchangeable or not. Thanks.