[unruhjonny]

I'm not exactly sure where to post this, so hopefully this is a fine spot;

I was wondering if anyone might be able to help me out with interchange, or if a suitable part is being currently manufactured to use.

I have a 1963 Muncie main case #3831704;
Long story short, my brother bought it, and I am wondering about the viability of using it - the thing is in perfect condition.
I have a 1968(?) M20 that has a repaired main case, and it could probably need a rebuild anyway, so I am wondering if I was to rebuild it, if it might make sense to rebuild it using this case.
(I could bore it for the larger countershaft, but the smaller front bearing would presumably have to stay.)

I understand from my 'rebuilding Muncie' book that the original smaller diameter front bearing worked with a specific very hard to find (aluminum) front bearing retainer, and that a saginaw front bearing retainer #592620 is a viable (cast iron) replacement;
I did some searches and it appears that this 'saginaw' bearing retainer is for a 1955-1957 Corvette, and there are at least three on ebay right now.

Question #1: Does anyone know the full application for the this "saginaw" bearing retainer?
(or was this specific to 55-57 Corvettes?)

Question #2: Does anyone know if a replacement (cast iron) front bearing retainer that would work for me is currently being manufactured?
(I bought a AGE front bearing retainer for another Muncie, and in addition to it being a great brand new part, it came in at less than OE pricing)

Question #3: Is it anyone's opinion that I throw away the idea of ever using this main case?
(Does anyone know if, or believe that this smaller front bearing will become an issue if I was to run it behind a Pontiac 400?)

Thanks to anyone who might speak up!