How hard/expensive is it to switch out gearing on an A-body?

Treblig said

I would much rather install a 2004R!! I'm running 4:56 gears and my car cruises at 2500 going 65/70 MPH (29" tires)....I love it. When I had 3:90 gears I could cruise at 70MPH doing 2100RPM with a top speed of 180!!!! Why spend money on switching gears when you can keep the gears and increase your gas mileage??
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treblig

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Replace a 4 speed with a 200 auto? Are you freaking nuts? Other them a medical condition you would have to be nuts to do that.

If you want od you can keep the 3:91 gear and just stick a passion od 4 speed in it. Not the 5 speed people are waiting years for but his od 4 speed. There's your best of both worlds and ya don't have to hack the crossmember or ruin the car by putting an automatic in the thing.