Paul,
It's like I thought: on my 544 there is no spacer as such, just the steel bushing that goes through the rubber "donut" and is just as long as the rubber is wide at the center. Donut and bushing fit snugly between the flanges on the tranny support cross member. I know that the parts manual calls #42, the steel bushing, a "spacer tube", but it is only a spacer in the sense that it keeps you from squeezing the flanges together on the rubber when you tighten the nut.

In your situation, I would just eyeball the flanges to 90°, jimmy the gearbox to the center of the tunnel, and cut a piece of sturdy tubing (maybe one or two large nuts would do) with a washers at either end to sit next to the "donut" to keep the tranny centered. I don't understand why that mounting bracket has to be asymmetrical, but then, there's lots of stuff I don't understand. ;-) I may be wrong, but I almost suspect that the rubber in your mount is not the original.

I suppose that on a 210 you don't have to worry as much about reinforcing that tunnel after cutting it as you do on a 444 or 544. That should simplify your life a bit.

Bob S.
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"62 PV544 (B20, M41), "71 142E, "93 240 Classic Wagon.