Ball lock posts, type A vs. type B

I recently purchased the 5 gallon used ball lock keg system from Northern Brewer and was doing a little research about the post types. I found that types A and B are the most common. My questions are; are the two types interchangeable? Do they share the same threading? How do you tell the difference between the two types? The used keg came with the gas side a little chewed up and would like to replace the post as soon as I can. Thanks for any help.

Look at your keg to see what style it is then find it on this link it should answer your question.

http://www.dresselbrew.com/Keg_Info.htm

I recently replaced type A posts with type B posts on one of my kegs. Works just fine, no issues.