Also, it appears that a few people are in the same situation i am in. The cars all come with solid front axles. So for now it is not an issue for me to run it that way and the rules may even change to eliminate the diff restriction. Also, 3racing has finally responded to me and confirmed that I will be able to use the 21M diff as soon as it is made available. The 21M kit is apparently available now, but the individual parts arent in stock yet.
Diff for 21M...
https://3racing.shop/products/sak-a5...009b8227&_ss=r
21M kit...
https://3racing.shop/products/advanc...ouring-chassis
Looks like the moved the motor rearward again, the belts arent equal. Maybe closer to the 60/40 of the S64 kit.