Does anyone know..
Will a A15 sump fit onto a A13 block?
Any known clearance issues or stud/bolt alignment problems?

The A15 sump will bolt to any rear distributor A series eng. The A15 sump has additional bulges in one side to clear the longer stroke of that engine.

None of the other sumps from rear distributor engines will work on the A15 because they do not have the bulges on the sides & the rods will hit.

The A10 & 1200 engines [front distributor] have sumps that will interchange between each other, but will not fit any rear distributor engine.

Thanks Dodgeman.

hi Dodgeman,

What is the difference between oil pans in front-dizzy A12 engine version mid-dizzy A12?

As far as I know, there were only four pans:
1. Front Sump (B10, B110, B310)
2. Mid-sump (B210, perhaps A14 only)
3. A15 pan with bulges
4. FWD A-series, cast aluminum front sump

Three pressed steel sumps for rear drive cars. [as far as I know]

A. A10 & 1200 [front dist engines] Different part numbers but interchangeable.
B. All rear distributor engines except A15
C. A15. This will also fit all other rear distributor engines, but not A10 & 1200 [front dist] engines.

When the dist was moved to the rear for 1974 there was a change in the pan rail shape under the oil pump area which prevents interchangeability between front dist & rear dist engines.
The lack of clearances bulges on the "B" type pans prevents use on the A15, however the presence of bulges on the A15 pan does not interfere with its use on other rear dist engines.

I believe that many sump gasket sets for A series engines come with three pan rail gaskets. On for the left side [all] & two for the two different versions of the right side.

Thanks. Make sense. I updated wiki - Oil pan with this information. There are pics of the different pans there.