727 Front Planet

Hey guys,

I'm rebuilding a 727, the front planet stripped out on it when the spiders in the rear end blew and locked the axle up.

The transmission is a hybrid of a few unknown 727's and I'm wanting to know if there's a surefire way to tell if I have the early or late output shaft. I have found what I was told is an early style planet, and it fits my shaft which from what limited info I have on the tranny is an early style as well. Just wondering if you guys have some tricks on determining this, I would like to avoid taking this thing apart again because the wrong planet is in there.

with such a bastardized version of a 727 you have now, IMO your better off either buying
a new one, or a known good used one.

It's a hybrid because its in an International Scout with a 440. The output and tail housing is unique to the Scout 727, the case is a standard big block 727. I assume the insides are original to the Scout which is a '74 but am not 100% sure that is the case.

oh it an I.S. then yah, it has an early style planet. didn't think the output
and tailshafts were that rare, don't early RAMS use the same setup?

The easiest way to see if the output shaft and planet splines match is to mount the front planet only on the shaft and shine a flashlight in from the back side, any mismatch will show on the light shining through the front.

Isn't the difference in the shape of the splines? I thought the early units used a rounded spline and the later ones went with sharper splines.

From what I've read the pitch of the splines changed and that it's very hard to distinguish the difference. The flashlight deal sounds like that could be the winning ticket or if all Scouts used the early style, even those build after 1975....

From what I've gathered you can't put a late planet on an early shaft, but both planets will fit a late shaft. I think I have the early style shaft, but want to make certain, without having to buy a whole bunch of planets and shafts to experiment with.....

The difference is in the angle of the individual splines.

The spline included angles are as follows:

'62-'75= 90°

'76-'93= 75°

'94-on= 60°

The spline angles are sometimes expressed as the pressure angle which is half the included angle (45°, 37.5°, 30°)