[THEFERMANATOR]

Originally Posted by Skools Out

the 78 will fit but you will have to swap the shift rods as the older one was off a cross flow and newer motor a looper they just use a different shaped shift rod that's all. they just screw in and out.

Now on a 20" lower unit the shift rod when you swap should measure 21 & 15/16 inches measuring from the surface where the gear case and midsection meet to the top of the shift rod when the gear case is in neutral.

What he said. If you have the 1.86:1 gear ratio, that 140 will never run right. It makes sense that a smaller prop should correct it, but the problem then will be that your top end will be slow even though your RPM's are there. And it will not pull well out of the hole.