I have four Contra's apart now and slowly putting them back together. Instead of one at a time, I'm doing assembly line fashion, which gives me a better opportunity to compare the bits from different saws.
I'm working on the flywheel side case halves now -- noticed a few differences, so I thought I would share.
First, the dowel pins that align the halves are different - either 6 mm or 8 mm in diameter. Second, some halves have three holes drilled through the case. Not sure what they're there for. They're not threaded. See the pic - circled in red.
Casting appears to be the same for the earlier saws, but the latest one I have is lettered different - larger font.
What's odd is that it doesn't make sense when you look at the serial numbers.
100598 - No holes, small 6 mm pins. Small font on part number.
158819 - No holes, small 6 mm pins. Small font.
176143 - No holes, large 8 mm pins. Small font.
187610 - 3 extra holes, large 8 mm pins. Small font.
364797 - 3 extra holes, small 6 mm pins. Large font.
I checked my NOS 070/090 case half - different part number, but it has the 3 extra holes and the small pins.
So, I'm thinking the 3 extra holes was a running change that remained, and the 8 mm pins proved to be a bad idea so they went back to 6 mm.
Scott