Thank you, Dan, for taking the time to do your research. I agree. The photo of the spring in my friend's side cover looks more like the offerings that you located than it does the spring in both my OD trans and in my straight drive version. I ordered the green box one that you show above. I will post how it works for me.

Again, thank you for your help!

Side note: I had a trip scheduled for last August, so I put my truck on blocks and ran the fuel out of the carburetor. Events occurred, so the truck is stuck in its current state for into the near future. Turning a negative into a positive I have been working on a long list of "maybe, someday" repairs, modifications and fixes, the biggest of those being getting a disc brake conversion working to my liking and getting this OD transmission working. I look forward to all of my changes being finished and working properly.

1950 GMC 100 Panel Truck, 1958 270,
3-spd Saginaw with BW OD,
3.73 12 Bolt Differential from a 1966 C10,
Front Disc Brakes
Bought it in pieces 9-1976, driving since 6-1978
Follow in the DITY