Mark IV A vs B

[Scrapinger]

Please forgive my ignorance. I have noted by reading different threads on this awesome forum that there is distinctly Mark IVa's and b's. What is the difference between the two. Are there performance differences as well?

I bought mine new last year and It's got a detachable power chord and is a short head.

 

[GD_NC]

It's all here in this thread: http://forum.grailtone.com/viewtopic.php?f=27&t=5987