Lower unit swap

[armadaplumb]

I have a working 1982 70hp 3 cyl powerhead without lower unit

i also have a rough running 50hp 4 cyl manual start same sort of age complete with lower unit type r drive? (with preload pin)

Can i use this lower unit as a straight swap for the 70, will it accept the preload pin type drive shaft and will the ratios be correct?

thanks

j