I have an S60 in my Duster. Have 4.30 gears and 4.56 already on spools. Really doesn’t take that long to swap gears and is certainly cheaper than a whole after market “pig” set up ready to swap. If you do go 9” do your homework on a housing that will hold up. Ladder bar kind of hard on stuff. My rear including rotors/calipers is 198lb.
My S/P car had a Mark Williams Dana 60 with his 40 spline axles and aluminum spool with a set of Pro Gear 5.87 ratio
, I replace them with a new Moser 40 spline 4 series spool and a used set of Dana stock 4.56 ratio ring and pinion out of a used pick up rear end rom a junk yard. I wanted to use a set of stock Dana 4.10 gears but no one makes a 3 series 40 spline spool
I can reinstalled those Pro gears by changing the rear pinion bearing shim by .003
Probably take me less than 2 hours now, I'm 76 yrs old and getting slower
The car had a all aluminum KB blown alcohol motor with B1 heads that ran 7.64 at 184+ MPH with the driver weighing under 2600 Lbs. is the story I was told.
I have a lot of runs on those used 4.56 now with a 400 stroker motor on E85, best ET so far is 8.86 at 150. MPH weighing 2850 Lbs. with me in it. No noise or problems with that dana 60 so far
