I had peviously posted RE rear end whining noise. Turns out the ring and pinion gears are badly worn due to a bad set up the mechanic thinks. It is a chrysler 9.25" 3.92 which all the parts guys are telling him to replace with the 3.90. Bad idea or OK?
Are the Dana Spicer replacement parts good or bad?
Thanks

 

You should check your owners manual and look at the Gross Combined Vehicle Weight chart. It is based on a combination of engine, transmission, and rear gears. Use that chart to pick a gear to match your towing desires.
Cheers, Steve

 

This issue is not uncommon. Ring and pinion gears require a specific backlash adjustment which must be done properly else they will wear prematurely.

Chrysler 9.25 differential ring and pinion gears are readily available from many sources. Spicer is adequate, better gearsets usually cost more.

29 spline
http://www.jegs.com/i/Motive-Gear/68...5-390/10002/-1

If you choose to refit your van to factory specs you will want the Dodge van gearset. Van gear sets are far quieter but cost more.

29 spline
http://www.jegs.com/i/Yukon-Gear/807...25355/10002/-1

If you wish to return to factory specs, replace them with factory parts. There should be a sticker under the hood and a metal tag attached to the differential which specifies the installed gear ratio. If your question is what is the difference between 3.9 and 3.92, there is no real world difference.

If you dont use the truck for towing you might want to consider installing 3.5 gears for better gas milage.

plain 29 spline
http://www.jegs.com/i/Spicer/094/2020609/10002/-1

van 29 spline
http://www.jegs.com/i/Yukon-Gear/807...25355/10002/-1


If you tow a great deal and have a small displacement engine I recommend you stick with those 3.9 gears and if you order these online please make sure the spline count is correct before you order.