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Discussion Starter #1
Hi All,

My untrained eyeballs don't see a difference between 750 & 101 differentials from the outside.

Can somebody post some photos showing the difference? (or are there any?)

Thanks,
Jon
 

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Discussion Starter #2
750 diffy

Alright, I guess I am going to have to approach this question in parts.

Part 1:
Do all 750 diffy's have the square flange like shown below?

Part 2:
Do only 750 diffy's have a number stamped in the side like shown below?

JB
 

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Hi Jon

I swapped the diff on my 750 Sprint with one from a 101 Sprint about ten years ago due to the trailing arm brackets cracking up on the 750 diff. I had both of them on the floor next to each other & I went over them pretty thoroughly and to my eye and tape measure there was no real physical difference.

The only external difference I found between the 750 & 101 diff was that the rear shock mounting plates on top of the spring perches were 10mm (1cm or just less than 1/2") taller on the 101 diff than the 750 diff. These can be unbolted & swapped over............it was such a PITA to get to the nuts that I didn't worry & my '57 has been running a 101 diff for years without any issue.

Internally it's a whole other ball game as the bearing sizes are NOT the same. The 101 went to larger bearings for better reliability / lifespan / etc, etc.......or maybe because the supplier took Luigi out for lunch a few more times ??

I have diffs with numbers stamped in them and some without, some with ratio's stamped on the side & some without, ditto with gearbox housings, so I'm not sure how accurate a measurement the numbers would be ??

Either way, as long as you have a 9/41 diff (4.555) albeit from a 101 Sprint / Spider or even a Ti, it'll fit just fine under the tail end of your 750D & keep the speedo accurate. It's not worth trying to swap side tubes from one diff to another - leave that to really talented guys like Richard Jemison and Gordon Raymond !!

Ciao
Greig

750B's
750D
10103's
10102's
10109
 

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I seem to recall that the 750 rear springs are 105 mm dia whereas the 101 springs are 115 mm diam. This would physically note the difference.
Of course there is the transition so who know what happens there.
 
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