What's the difference in the 500 and 505 gears? I need a set of as gears for my 505 what to do.
505 are a little faster, but a little weaker.
You could install the 500 in the 505, but you couldn't install the 505 in the 500, unless you customize the pinion.
Here is the chart for the Jigmasters:
https://www.mysticparts.com/PennParts/ReelSpecs/PennJigmaster.aspx#specs (https://www.mysticparts.com/PennParts/ReelSpecs/PennJigmaster.aspx#specs)
"Edited as per Moderators to correct Scott's Bait & Tackle over to their new store name Mystic Reel Parts / www.mysticparts.com"
Did you order a set of 5:1 stainless steel gears from Black Pearl? If you did, they should work out just fine in your 505.
If you wait till next week I will let you know for sure on how they work.
You probably won't have a choice, Penn only sells brass main gears for those.