Pinion seal replacement 8.75 742 case.

Need to change the pinion seal on my 742 case. Been trying to find a replacement seal and the parts store keeps telling me there are several different sizes. WTF? Are there different ID and OD dimensions for a 742? And what is the torque setting for tightening the pinion nut?

742 case is a 1 3/4" diameter pinion I believe. 1.375/1.38 is the 741 case and the 489 is 1.875".

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Need to change the pinion seal on my 742 case. Been trying to find a replacement seal and the parts store keeps telling me there are several different sizes. WTF? Are there different ID and OD dimensions for a 742? And what is the torque setting for tightening the pinion nut?

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Ask for and buy both pre 1968 or older 8 3/4 pinion seals in the catatlog and bring the one you don't use back for a return, most auto parts stores will do that when there is more than one part number for the same year car and parts involved I use 150 ft lbs on the torque wrench and then add some pull to make sure thier tight If your changing the seal in the car you will have a hard time getting that much torque on it without a really good air 1/2 inch Hipo impact gun I use a big pipe wrench on the pinion yoke to hold it while tightening the pinion nut, it helps to have a helper hold the pipe wrench so you can use both hands on the torque wrench to pull with