'64 C60 with the 15k lb Chevrolet two speed vacuum rear axle (with the 15x4 brake shoes). Everything I reference notes that the axle is the same from '60 thru roughly '72 on the trucks so it shouldn't be model year specific.
I pulled the yoke and oil seal retainer housing from the axle to replace the pinion oil seal and pulled the main cover to drain the diff and clean and replace fluids. Both had a cork gasket. None of my books show a part number and the local NAPA looked at me cross-eyed when I asked about them. Is the gasket necessary or will some liquid gasket maker cut it? The way the yoke is torqued to the pinion shaft I cant imagine the absence of a 2-4mm gasket messing with bearing preload or oil seal.
Additionally, the manual calls for a 'felt washer' to be present between the oil seal housing and the oil seal itself (see attached photo). There was most definently not one present when I took it apart and the part number on the old seal matches factory numbers which was only run from 64-66. By my guess, I am the first person to have this pinion apart based on what I am seeing, thus I assume the washer was omitted at the factory? Any thought on trying to source one or running without it?
And for anyone that searches and comes across this thread, here's some useful info: PN: 3826129 is the original OEM pinion seal for this axle from '64-'66 PN: 3879527 replaced 3826129 in '66 as the OEM pinion seal
PN: 411330N is the NATIONAL pinion seal that interchanges with both above OEM seals and is available new PN: 25970 is the SKF pinion seal that interchanges with both above OEM seals and is available new PN: 411330N is the TIMKEN pinion seal that interchanges with both above OEM seals and is available new
Managed to obtain a master parts manual spanning 46-72 medium duty.
The 'felt washer' also known as the Packing - Pinion, Seal that is referenced above and appears in the '63 shop manual and is referenced in the parts manual as: - The '55-'70 15000 lb & 17000 lb Two speed rear axle group Group 5.469 PACKING - Seal, Pinion PN:3653617 - The '60-'72 Series 60 15000 lb Two Speed Rear axle group No felt seal present
The Oil Seal Retainer Gasket - Group 5.476 '61-'66 Ser. 50-60 w/15,000 lb axle PN: 3758222A.R.
Axle housing gasket - Group 5.508 GASKET, Axle Housing to Differential Carrier '64-'66 Ser. 60 w/15000 lb axle PN: 3762399
None of these gaskets are manufactured anymore but apparently occasionally pop up as NOS (though very rare). Your best bet is to just use liquid gasket maker and keep an eye on things, unless someone has a better suggestion.
As to the 'felt spacer' I referenced above, I have two instances of this axle in the parts manual with one calling for its presence, and the other not. Given the lack of one on my particular axle during teardown and the indications that appeared that I was the first one in there, I assume its presence is unnecessary and thus will reassemble as it was originally assembled.