This weekend I pulled the engine and trans from my 69 GS 350. It has what I believe, but may be wrong, 66 M20 in it. Prior to pulling I read to drain trans oil or it'll get all over the place. So I pulled the fill plug (square bolt) on the passenger side of trans about half way up, to see if anything would come out, nothing did. Didn't stick my finger in there to see if I could feel the fluid, I know I should have. Decided to pull trans anyways and just put a drain pan where the drive shaft meets the trans (not sure what it's called). Pulled it all the way out and i got may a drop of two of fluid. Was expecting much more. This common? Could this mean that I dont have any/much trans fluid in there? Anything specific I should check for?
Make sure to use GL-4 gear lube. Do NOT use any lube that has GL-5 on the bottle. GL-5 gear lube is missing important additives to protect the brass suncho rings.
Not to many gear oil GL-4 is made for our Muncie. The only one I use and never had a problem is Sta-Lube GL4 (85W90). I still have my original Muncie in my 71 GS350 4 speed car and it still shifts like butter!
Answering the OP's original question, if your driveshaft was out and there was no yoke on the output shaft when you pulled the engine/transmission, and assuming that you had to have a pretty good angle on them coming out, you should have poured quite a bit on the ground. So, yes, it was low, very low on gear lube. You may want to take the side cover off and look at the gears/synchros for abnormal wear. From your description, the plug you pulled out actually WAS the fill plug which works like the fill plug on the differential. (Pull it out, check for fluid with your finger, add till it just runs out). Hopefully you won't find much wrong. Were you having any shifting issues like popping out of gear, hard to shift, grinding, etc?
@GS464 thanks for the reply. So when i pulled the motor and trans the front end was gone so not much of an angle. I pulled the plug and stuck my finger in there, didn't feel any trans oil. From watching videos i assumed the oil would come pouring out, but nothing did. When i took it home i did notice some oil on my trunk mat, not much though. I'll open it up and take a look at the gears. Not real issues with shifting but i only drove it for about 2 hours prior to starting my tear down.
If you have it out of the car, can't you just turn the trans over on its side, and see how much oil comes out of the open fill hole?