I pumped to this old thread when I tried to find out about Sierra 1.3 OHC diff ratios. I have quit early 1.3 5 door Sierra GL (with turbo installed when new) and I'm quit shure finish user manual listed it as having 4.xx diff. It is in quit hard place to reatch now so I report back when snow melts if somebody is still interested. I have many Sierras and parts so I have looked at it and drive safts and shell are smaller than 7". Turbo Sierra has now 7" ZF diff and whole axle but I saved the old one.

Vin plate said axle B so it's 3.77 but there are letters and numbers for over 4.xx ratios and I'm still sure that I have seen ratios over 4 marked for 1.3 OHC.