Differential service/ replacement

[seniorchristo]

As discussed previously, due to excessive noise and the desire to have more relaxed cruising, I will be swapping my diff for a used one. Originally I thought I had a 3.9 but after recalculating I believe it is the original 3.77 as per 1967 S3 SE. I found a 3.55 which appears to be very smooth with no leaks. Not being able to verify its internal condition, I thought replacement of seals and bearings may be appropriate. I have three trains of thought here.
1) leave well enough alone and don't mess with it.
2) replace the pinion bearings, seal and crush washer only (since these are difficult to do in situ)
3) replace all seals and bearings and inspect internals
There seems to be about 1/8" inch of play/movement at the perimeter of the input flange on the 3.55 diff. Does anybody know roughly if this is normal?
While checking out Youtube for Elan related videos, I chanced upon one of Cal Croucher explaining how to simplify diff removal. It included advice on rounding off corners of the diff and other suggestions. I use his CV axles and may use his advice here. Has anybody else seen this video?
Thanks and Happy Holidays
Chris

[elansprint71]

I have not seen the video.
Diff removal is no big deal, it usually refuses to budge then falls out crushes and your chest- keep you head out of the way.
Fit the 3.55 and see how it goes... that amount of play does not surprise me.
Incidentally, when I changed a 3.77 for 3.54 (Escort diff) I did not have the correct speedo drive-gear to hand; turns out that the 3.77 drive-gear gives the exact speedo reading checked against my GPS.

In the meantime get your 3.77 rebuilt and put it on the shelf.

[seniorchristo]

Good advice Elansprint. I'm going to do just that!
Thanks,
Chris

[Famous Frank]

I'm leaving mine a 3:77 although it has a limited slip, and installing a 5 speed. The 5 speed is installed but i haven't tested it yet. Soon though!

Either way, lower revs will be a delight!

Frank