Check out this site it has some information that will help
http://www.gearheadracing.com/Refere...sID/muncie.htm
M22 has a different gear cut than a m20 or m21,the m22 gear cut is more straight than angled,which helped it to shift into gear easier,but also made it more noiser,also a m22 is a more stronger trans than a m20 or m21.Some m21's used the same cases and input shafts as a m22 also.A couple of tale tale signs to look for is.
1. All m22 trans has the drain boss drilled and tapped and a plug installed
2. All m22 trans had NO ring grooves around the input shaft.
3.. The way to really tell for sure is pull the side cover and look at the cut of the gears!That is the best way to tell and if you are buying a trans you need to pull the side cover anyway to make sure it is not damaged or worn really bad!
Prices range from around $800.00 and up to $$$$! Depending on date of trans and it's condition.I have seen some M22's go for as much as $2500.00.Of course if you was to happen to run up on a NOS there is no telling what it would bring.
Hope this helps
Bobby Dodson