If I understand correctly, I need to have them press off the 18 tooth Dynaflow gear (from a 3.6 rear end), and also press off the 22 tooth manual transmission gear (from a 4.1 rear end). Is the reassembly step to simply have them press the 18 tooth gear onto the shaft assembly that formerly held the the 22 tooth gear
Yes, you have described the procedure pretty much as I did it. I would add that once the shaft has been pressed out of the gear, the shaft will either fall out of the sleeve from its own weight or else you can easily pull it out with your fingers. At this point, it might be a good idea to inspect the shaft and the bore in the sleeve just to head off any surprises later on.
When reassembling, press the gear partway onto the shaft first, then insert your feeler gauge (I used .006) between the gear and the end of the sleeve to set the endplay, and finally press the gear till it touches the feeler gauge. The shop should know how to do all of this anyway as long as you tell them how much endplay you want.
or did you disassemble the (now) gearless Manual speedometer driven gear assembly, press the 18 tooth gear onto the shaft, and then reassemble? Before reassembly, did you first grind a short, steep taper onto the end of the shaft? I ask because your experience suggests that these speedometer driven gear assemblies were originally made by pressing the gear partway onto the bare shaft (when it is very easy to align the shaft and gear), then joining the shaft to the case, inserting the keeper, and finally pressing the gear further onto the shaft to meet the specified 5-10 thousandths clearance.
No, I made no attempt to remove the retaining washer from the shaft because I didn't want to risk damaging the washer.
The end of the shaft was already chamfered on mine, so you probably won't need to grind a new chamfer on yours unless you had to grind the end of the manual shaft to get the gear off of it in the first place. On mine, it was the Dynaflow shaft that had been peened, not the manual, and of course I wasn't intending to use the Dynaflow shaft again. The bore in the gear should also be chamfered on at least one end, and this is the end that should face the sleeve upon reassembly. If both ends are chamfered, install the gear with its part number facing out.
My guess is that the factory pressed the gear onto the shaft (to its final position) before the shaft went into the sleeve. The washer would have been installed as the last assembly operation. I think this would probably be the most efficient way from the manufacturing standpoint if they had to assemble thousands of these things.
I think you will like the combination of the manual transmission and 3.6 axle gears. It is very easy to get the car moving from a standing start with this setup, even uphill. IMO, this is how Buick should have built the car to begin with.
Ray