7 1/4 Rear End clean up/gasket questions

geminimotors said
My 7.25 has a nylon washer on the fill plug. @ 3/4” ID, 1” OD. My local Ace hardware has em.

Thanks! I'm no stranger to buying car parts at the hardware store and in fact I have to make a run there for a random assortment of nuts and bolts anyway, so I'll grab one of these while I'm there.