My F-150 4x4 supercrew was in an accident, the body shop replace the whole rear axle(the axle and housing was bend). The truck had an 3.55 limited slip axle,they said that was what they had order to go back in!Until Friday I had no problem,I was backing up a grass hill with a trailer about 5000 lbs heard a pop and the back wheel started spinning.The tag on the rear end reads L 559 75 0B20 S 941 A The other tag reads 75W 140 SYNTH OIL ONLY.Thanks for any help.

 

Welcome !! If you take a closer look, you should see that your code is missing the first character which will be a "3". This combination shows a 3.55 LS 9.75"