I'm looking for an article ! It's in the October 1979 issue
of Popular Hot Rodding about $1.98 posi reffering to installing shims in the spider gears ! Can anyone help ? What I'm trying to do is to create a positive traction unit in my wifes "79" F-150 that has a 9" rear without welding the spiders or installing a spool ,this truck is street driven and the local salvage yard wants big $$$ so I'm looking to do this in an inexpensive way ! If anyone can help it would be appreciated !! Thanks in advance ! ...cougar...

Posi-Traction is a GM differential

Maybe try looking for a Ford Traction Lock or Limited Slip article .

see this article

http://www.kevinstang.com/Ninecase.htm

ok i have done the extra shims in the past all ya do is take the diff apart then and 3-4 shims to each side of the axle spiders. put it all back together and hammer it tight with an air gun. the only draw back to this is being street driven you will have to re do it about every 100 mile as from turning corners itll chew up he shims! and all the metel flakes from the shims will chew up the bearings in your diff. so what "I" would do is for 50 bucks install a mini spool and live with it. lots of folks will say you cant run a spool on the street but i personaly have put about 50k on a spooled rear axle with 0 trouble just a tad bit more tire ware,ya just got to learn how to drive it thats all