Hey All,

I'm gathering parts for my auto to manual conversion. Is they a stamping or part
number on the diff which tells the difference between auto and manual diff.
I've found two local seller in SoCal and want to make sure I get the correct one.
Do o need the manual drive shaft or could I use the auto shaft with manual input shaft?

Thank you, Jay

 

The auto 3.909 diff had a larger diameter flange on it. The only way the standard drive shaft will mate is to drill 4 new holes, or replace the flange with one from a standard diff.
Do the rotational test of the input to output to determine the gearing. Very simple to do!


If you are planning to run higher power on your standard trans conversion car, keep the auto diff and install the .806 JDM 5th gear.

 

I'm getting ready to swap as well but I'm keeping the auto diff. The difference between the two, from what I read is of course the gearing, but it really makes a minimal difference. To answer your question, I'm sure they have different part numbers. To answer your other question, you must use a manual driveshaft with the manual trans. An auto shaft and manual trans won't mate up. I bought a manual companion flange for the auto differential so I'll be changing that out to accept the manual drive shaft. You can keep the entire auto differential and just use the manual drive shaft, but you will have to drill four corresponding bolt holes in the auto flange in order for the shaft to mate up to it.