Confusion about 833 4 speeds

OK, I have a 74 Duster that I have converted to a 4 speed from the 904 trans. The trans that I bought was a OD unit and I am not real happy about how it works. I recently purchased a 4 speed unit from an individual on this forum and have discovered a few issues. First the cast marking are

Bearing retainer: C94769 UF4
1964-1975 A-body, and 1970-up E-body small block 23 spline transmissions with 307 front bearing, 4.354" outside diameter, 3.70" bolt circle, replaces cast #C94796 original retainer. Gasket and seal included.

Main Case: C97372 A3 and 11-28
Cover: C95664 3 1X5
Tail Housing: c96706K

Date: 10-18-66

I have counted the output shaft splines and there are 26.

The first issue I have is with the output shaft and yoke. I have had my drive line modified to take the 30 spline yoke when I installed the Overdrive trans, but it seems that the 4 speed I just got has a different spline shaft of 26.

1) Is this the same as the 904?
Yes, Kinda

2) Can the output shaft of the 4 speed be upgraded to a 30 spline shaft?
yes, but you have to do #3 also

3) If the shaft is changed, can I use the Overdrive units tail housing?

I wish to rebuild the 4 speed and need to know what parts kit to buy.

1) Based on the info provided, Can anyone ID what Syncros and bearing kit I need?

I still have not removed the Overdrive trans from the car, but I am wondering if the bell housing will swap over. The 4 speed trans bearing retainer looks to be smaller that the overdrive trans bearing retainer, but I will not know for sure until I get the trans out of the car.

Brewers sells the OD Bearing retainer for the 3.70 bolt circle. then it will fit your bellhousing. I usually buy the inner countershaft shaft, all bearings and rear bushing, Gaskets, and small parts package. If it was mine I'd replace both shift forks and both synchro assemblies, the newer ones are supposed to shift better. This assumes everything looks like new. It should run like new for the next 100k miles if you use 90 weight gear oil. The trans sounds like an original 66 or 67 A body trans. You will need new shifter linkage but the shifter is good to go.

Can anyone give me some pointers on rebuilding this 4 speed and what to look for. I opened the case and all of the gears look fine, no missing or broken teeth as I can see. I am a Airframe and Powerplant Mechanic and have plenty of gear head knowledge from aircraft engines and that sort, so I am not worried about getting the job done. Just wondered if anyone had some info to help. Thanks for taking the time to read this and hope you can help.

Clean up the burrs on the shifter shafts, where the arms bolt to, before you push them out. You should be fine. You can do the same to the OD and tighten it up like new also.