I would like to get lower rpms on the freeway in my '85 300cd. I have never messed with this kind of stuff before, so bear with me.

I read from a search that there is a list somewhere of stock diff ratios. From there, what car(s) would have my best bet for a replacement part? Is it just pop the old one out and the new one in?

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My Primary Driver - '85 300CD - 4-speed conversion, 2.47 rear, lowered, euro headlights, rebuilding (not restoring so much)

Wife's - '08 Saab Sportcombi Aero

Riding a '03 Yamaha Warrior