There should be no difference but, unfortunately, the gear case must be
taken completely apart to change the drive shaft. I ran into that last year
and to take both the old and new apart, change drive shafts, etc. made a
"deal" cost prohibitive. If you can find someone who will furnish you a
guaranteed (long shaft) one at a price you can live with, then go for it.
For my 200 merc, I got one for $450 that continued to leak, eventually
swapped it for a $1000 which has worked good and I trust the guy I got it
from!
LD

"Tom Creech" wrote in message
...
I need a new lower unit for my 1979 70 hp Mercury outboard (long shaft).
I've found one, but it's for a short shaft). Aside from the length of the
drive shaft, is there any difference in the two?

Thanks,

Tom