Hi Rocker. I also have a cobbled together transmission in my '36 Chevy pickup. It was assembled from new parts from various sources in the early 1970s. Right off the bat it was noisy in first gear. I disassembled it and replaced the new first gear from Republic Gear with a good used gear from GM and the noise was gone. The next problem is that it did not shift smoothly from 2nd to 3rd once it was warmed up. That problem persists to this day evcn though all new parts were used except the first gear and the end play of the synchronizer parts is shimmed to the precise middle of the .025"-.035" specified end play. It is better with more viscous oil, presently "600W" from The Filling Station, but not really working properly.
I recently picked up a complete transmission from a car and I will either put its innards into the case I have now or more ideally find an empty case to use so I can leave the present trans intact. The case I'm looking for was used in '32-'33 "Eagle" or "Master" cars and in '34-'36 pickups. If you might know of one out there the casting number on the case is 590532.
I'm hoping that a set of gears that has been together forever gets along better than a "cobbled together" set.
In the 50 years that I've been interested in this hobby I've never heard of a "break in" period or procedure for a transmission, but we learn every day.
As for GL4-GL5, I read the information on the containers. I've also read that the substance in GL5 that can harm brass can only do so at high temperatures that are unlikely to occur in a transmission.
