From Truckrolet:
And whats with the old car manual deal? Like the dealer stocks them? Sure.
I think (maybe

) what bouymaker was trying to do in posting the link to the manual, was to provide a resource listing that gives not only the "different" part numbers and applications for the variety of dipsticks (depending on the application/engine involved), but more specifically too help identify the correct dimensions (length) that applied for each of those items. The listing carries over to the next page in the manual (you can see just be clicking "Next Page") and each part is identified by a specific length. Different lengths equate to different level readings, yes/no/maybe so???
In my thinking, using that information would help make sure you get the correct length dipstick (one size does not fit all) for your application.
There have been a bunch of past conversations (Search the Site can direct you to them) about the correct dipstick length issue as it helps you make sure you are keeping the correct level of lube in your engine. Too low and damaged internals can ensue. Too much and you get blown seals and leaks galore. In both cases

Thanks to bouymaker for providing the useful info.

As others have already noted, a salvage/wrecking yard "may" be a source. You could also post an ad in the Swap Meet "Truck Parts Wanted" forum for what your looking for. Good chance some fellow Bolters could help you out.
Good luck on your search.

EDIT: TC beat me to the punch about the dimensions/length info with much a much more detailed list.
