Johnson 1961 vs. 63 lower units

[DanLieffring]

I have a 63 Johnson 40 horse model RDS-25D. I've been having some lower unit issues. I've just picked up a 61 Johnson 40 horse model RDS-23. I'm assuming both lower units are the same, and I can swap one unit with the other.

Can someone let me know if this is or isn't the case?

Is there anything I should look for when swapping these out?

 

[jay_merrill]

Re: Johnson 1961 vs. 63 lower units

Put the two gearboxes side by side and examine them. Are the water tube receptacles the same? Is the bolt pattern the same? Is the shift rod location in the same place? Does the driveshaft fit into the pinion gear properly?

My guess is that you will be fine with this swap. If all of the above seem to be the same, try fitting the replacement gearbox. It will either work or it won't.

 

[samo_ott]

Re: Johnson 1961 vs. 63 lower units

Somewhere in the 40's run they went from a one line pump housing to a dual line pump housing... Not sure when though...