The worn out rear end I took out of my '62 was a 4.56. The replacement axle (from a '67 122 wagon) was a 4.10. I've driven my car hard near redline on short Freeway blasts up to 5 miles a piece. Yep, it's loud, but a healthy Volvo engine should be able to take 3,900rpm for days without getting hurt. See it as an Italian tuneup. VWs and Porsche 912s are actually liking to rev and from my days in Germany I remember vividly hours of pedal to the metal and then lift the right foot about half an inch and turn up the radio.

Here's a thought: pretend your car's top speed is limited to 65mph, and you should be fine for even extended Freeway trips.

If your car's primary duty were to do Freeway commuting, I's suggest an overdrive trans, a T9, or a different gear ratio, but folks in the 1950s and '60s didn't have these options either and did just fine.

Once my new B18 engine is broken in, I'll be cruising at 70mph again, on Mobil 1 no less.

Bernard
(Car's story now on 6 pages.)
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www.californiaclassix.com/Bernard/PV544-1.html