High Frame Low Frame....

Austin produced different crankcases for different chassis, in later cars (32 on) there were high and low frame crankcases. The top picture shows a high frame crank case, as fitted to late vans and Standard engined Nippy's. The bottom picture shows a Low frame crankcase, which the majority were.
The easy way to tell them apart is by the clutch stop position. You can see clearly that the stop possition on the high frame(top pic) is blended into the flange fot the starter motor. And the low frame is a separate feature as shown(bottom picture).

But....
"Be warned!! The high frame crankcase can be fitted in the low

frame chassis with additional packing under the rear engine mounts. THE LOW FRAME CRANKCASE WILL NOT FIT IN A
HIGH FRAME CAR. This is the cause of late box saloons with the nose piece casting colliding with bottom of the hole in the radiator shell (unless the hole is enlarged), it also makes it near impossible to remove the flywheel cover and there are often issues with the propshaft joints touching the floorpan etc.YOU CANT TELL THEM APART BY ENGINE NUMBER the production overlapped here there and everywhere."