Crankshaft differences between '74 and '83

[Gunter]

Trying to figure out why the flywheel-end on cranks (And cases) looks different between '74 & '83.
Was there a change in design so that there is no longer a seperate thrust-flange on the crank starting in '78 with the SC's?
In Wayne's book, I believe he shows a 2.7 liter for the rebuild and the crank looks different than a crank from a 3.0. on the main seal end.
Wish he had used a 3.0 for the rebuild.

Is the seal for a 2.7 smaller than the later 3.0 and 3.2?
Consequently, is the recess for the seal on a 2.7 case smaller than on the later engines?

Many thanks.

[Henry Schmidt]

In 1978 Porsche changed the crank / flywheel from a 6 bolt to a 9 bolt flage configuration.
The 9 bolt crank flange is larger in diameter and as such requires a seal of a larger diameter.

[Gunter]

Thanks Henry:
That explains why one would see the bearing support with the holes in it when removing the old seal after '78 (9-bolt flange)
Before '78, one would see the thrust flange of the crank because the seal-diameter is smaller.
It had me puzzled.