Pinion Flange

[racer92]

Hello
I purchased a 390 R180 diff and it has a round pinion flange instead of the square shaped one which my 73 240's original diff has. I would like to know before starting to swap them over if the flange has to be changed/swapped from the original? Any help would be much appreciated thank you.
Joe

[Ont240]

Check the bolt spacing. your original is rectangular not equal between centres on the 4 holes. best way is to check it with your driveshaft. If the round flange is equally spaced you will need to swap.
Caution don't use an impact to put the nut back on or you could over tighten and mess up the preload.

make yourself a flange holder
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[racer92]

Thanks for the info so I guess the the flanges are interchangeable as far as number of splines and diameter of the pinion shaft.