I just picked up an older D3. Looking for a good source for filters and maybe a parts number list for the filters as well. Any help would be greatly appreciated.
Convenient, your local Cat dealer. Cheap, (if you have enough filters to order to balance the shipping) filterspro.com. that's filterS pro. They have filters for nearly anything, and cheap if you don't mind donaldson, baldwin, some wix.
You obviously don't have a Parts Manual or you wouldn't be asking for Part Numbers. Do you have an Operation & Maintenance Manual..? Probably the best $40 you'll ever spend.......... go to the link below and plug your machine Serial Number in the Search box. https://servicemanualpro.com/
I just picked up the machine on Saturday. I did'nt get a chance to get a parts manual yet, but it is on my list.
Personally I would suggest the O&M Manual should be top of your shopping list.