I have a 2000 F-250 S/D and there is diesel leaking around the shaft on the water drain valve. My question is, can I replaced the seal/o-ring or do I have to replace the entire drain valve and the housing? The leak itself is very slight, but the odor in the cab when sitting will gag a maggot. I know to an oil field hand it smells like money. Thanks ahead of time

I would check a parts store and the dealer and check what parts are available. This usually determines what repairs you make. Getting parts usually takes longer than doing the job.

I purchased the orings from Pure Diesel Power for $12.00 on the internet.
The orings are 1/2 O.D x 1/4" I.D with a 1/8" cross section. Save yourself some money and go to an oring distributor on the web and buy them. The job took me about 2 hours and I am a slow mechanic.

Did you try a local hardware store for o-rings? $12- seems high.