This technique is used by truckies to shift gears, you match engine rpm to driveshaft rpm - as everyone did when grampa was a young lad. Synchronizers are a blessing.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)