I have a 68 Dart with the stock rear end, and recently came into possession of a 3.55.
The Car isn't a long haul car, and doesn't see freeways at all. Its normally driven in a two mile radius of home, so I'm not afraid to give my old girl alittle more power to the rear..

Handy with a wrench, but not overtly experienced with a car, what tips, tricks, words of advice, ect can you give me.
I've seen RTV mentioned for a rear gasket, but I'm sure thats not OEM. Recommended brands, ect

Will we need a gear puller? Looking for my auto books now, but I "Cleaned" (you know, make it look nice but you cant find a thing) So I thought I would ask as I look

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My Car Domain

What size rear end? If it is a 7.25" you will need a special tool to get it apart.

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1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing

Well, special tool it is. Not to ask the obviously dumb, but needed question. "What tool"

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My Car Domain

I think he's talking about the adjusters at the inner end of the axle tubes. A B-body torsion bar has the right outer hex dimension 1 3/8", or you can weld a nut to the end of an A-body torsion bar. The adjusters need to be backed out before you can remove the ring gear carrier. The early ones used shims instead, which may be the case for your '68. I just went through this with my '67. I fabricated a tool, but then didn't need it. Typical for how this latest round of repairs has been proceeding.

The way I read this is that you have a new ring & pinion "gear-set" for a 7 1/4 that you would like to install into you current axle housing... correct?

Or... do you have a used axle assembly, with the 3.55 ratio?

To swap-in a new axle assembly is no problem, to correctly set-up a new ring & pinion gear set... that job takes some special tools and knowledge.
The main concern with setting-up a new gear set, is correctly setting the pinion depth, using shim(s) under a large, pressed-on bearing. If you do not have a selection of shims and a press... you will not be able to successfully accomplish this part of the job.
DD