Any of the clutch assemblies sizes will work with a 1953 truck clutch housing. You just have buy the correct size/assembly for the flywheel.
Buy an entire clutch assembly (all parts in a "kit").
This way, they will all match.
- clutch disc
- pressure plate
- throw-out/release bearing
- pilot bushing
- plastic clutch alignment tool
There were different diameter clutch-disc/pressure plates. You have to find one that matches the attachment holes in your 12v ring gear fly wheel. Good luck with on-line listings, because, as you have found, they have interesting ways of measuring diameters.
Also, you need matching parts because the clutch release-bearing height must match the pressure plate height (there were two height combinations).
I try to get a local parts supplier to order a set with all the parts. Ask them to determine what set you need. I have even brought in my flywheel, so they take responsibility for getting the correct assembly. This way, if it is not correct for your flywheel, they are more likely to refund/replace/reorder.
Check your flywheel for check-marks and glazing. A good parts place, like a big NAPA store, will turn/surface the flywheel for $20-$50.
Regarding the pilot bushing - let's hope someone posts info on any oddities related to a Poweglide crankshaft end (where the pilot bushing is installed).
