lower unit compatability 80 V4 100hp to 87 V6 150hp

[roger.st]

These look the same on the outside. Both have 20" shaft.I dont have them out. Is there a difference in the shaft?

 

[AEROCOOK]

Re: lower unit compatability 80 V4 100hp to 87 V6 150hp

Gear ratio is different, not sure what else.