The original rear axle would have had a 4.57 ratio, or higher. With the 3.90 rear, the 3/4 should drive very well... I have to assume it's not the original rear axle, or else the P.O. also has a concession for hen's teeth! LOL! Even if it's a 4.10 it should do decent highway speeds. The original trans should be the granny-low 4 spd.
My only concern would be the same trouble I'm having: finding replacement brake drums. The shoes can be relined, but the original Huck-style brake drums aren't available new any more, and even used can be rare. If it has a newer rear axle, parts will be easier to find for the rear brakes. Parts for the front, if they haven't been switched to Bendix-style, will still be difficult to replace.
Current fleet (subject to change w/o notice) \'49 GMC 3/4-Ton , 60 Austin Healey Frog-eye Sprite (some assembly required), 2011 Dodge Avenger, 2015 Jeep Cherokee. No, they don't all run. My other ride is a (B737)no, (B767)no, A320.... Update... was Embraer E190, now Boeing B787. Knowledge is a wonderful thing, but ignorance means you don't know you can't do something.
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