so i finally got enough mnoney for a new rear and wondering which to go with. I want it to last cuz its a weekend warrior but will be going high 9's by next summer. I drive on the street alot to. I would like to save a little money by keeping my disc brakes off my 84. I plan on doing a spool with 4.11s but not sure what spline to use either. Any opinions

 

As with every other post about an aftermarket diff, your choices are a 9", 12 bolt or Dana 60. Each has advantages and disadvantages. It's more, what do you want to use?

Your cheapest option is to go with a 9" housing package which includes axles. You provide the brakes although I don't think the older cast iron caliper brackets will work without some modifications. You also provide the center section which you can easily grab from a local junkyard until you're ready to upgrade. Buy the housing package with 31 spline axles then find a junkyard center that came with 31 spline axles.

If you're going to be using a 3+ speed transmission then going to 33 or 35 spline axles will be better however there are no OEM axles that large.

Ford diffs came with 28 and 31 spline axles and I won't recommend 2 spline even for a street car.

The 12 bolt and Dana 60 come with 30 spline axles. Both can be upgraded to 35.

One advantage with the 9" is that there's no series for the carrier. If you buy a spool and have 4.11 gears on it and in the future want to upgrade to a deeper ratio, you won't have to buy another spool.

On my 9", I use a Moser bolt through aluminum center case, an aluminum Daytona pinion bearing retainer and an aluminum spool. I can lift the center section in with one hand.

 

yea its a three speed tranny and i plan on buying all brand new from spohn most likely so junkyard parts and putting one together isnt a issue i just wana make sure i buy the right set up