One more thing, the A413's differential is the weakest link in the entire drivetrain. If the weight difference between both front left & right tires is more than 100 pounds (may vary, but I base this on my experience), only one tire will spin during a burnout. The differential crossshaft will then gaul up and break the retaining pin. When this happens, the shaft slips out of the differential and collides into either the cover or the housing. Big mess either way. You have several options:
1. Mopar retaining pin clips. Paul Smith shows the part number and how to install. I currently use these along with having the front end weight balanced. So far so good, but I know it's a matter of time before the big "boom".
http://www.turbovan.net/Trans3.html
2. Phantom Grip. Never used it, but I've heard pros & cons. Paul Smith's webpage shows it also. If the side gears aren't machined perfectly flat, it will most likely not work.
3. Buy either an OBX or Quaife LSD. These are designed for manual transmissions, but can be made to work with an A413 with a ring gear spacer & cover/housing modifications. Art Leong has excellent details on how to achieve that.
4. The Cadillac option, buy a A413 LSD from Gary Peloquin. A bit spendy, but no mods needed as its a direct bolt in!
http://www.peloquins.com/products_A413.html
Good luck.
Rich