Installing new Hurst competition shifter/linkage on Muncie M21. The arms that bolt on to tranny (1-2, 3-4, Reverse) don't fit. The oval slot in the arms are to small, not tall enough. Am I missing something here? Probably 1/8 to 3/16 different. Also arms are not notched for 3/8 bolts to pass thru them?

What year is the trans and what year is the install/shifter kit for? The shift arm mounting type changed from "stud" to "bolt" at some point (69 I think, but not sure...) and I'm pretty sure the shift arms are not directly interchangeable...

See if your arm numbers match the current install kit (http://hurst-shifters.com/hurst-shifter/PDF%20Files/instructionsheets/3733163.pdf?ck=Yzh2wTBXAVsREfwZ&vid=Yzh2wTBXAWAREbcl&cktime=87856) numbers.

From Crash over in camaro-land:
The slot on a stud style lever (68 and previous) is .600"...
The slot on a bolt style lever (69+) is .750"...
A bolt style shift lever will fit a stud style shift shaft, but sloppy..
Hurst makes whats called a "bat wing" washer that takes up the slop...And here's (somebody else's) pic that shows the comparison:
http://mysite.verizon.net/bertfam/shifter/68-69arms.jpg

Sound like you have a '69 trans and a '67(?) install kit....

Arm numbers match sheet. Did the "stud" type transmission arms have a smaller hole than the "bolt" type?

Here's the bolt type install kit (http://hurst-shifters.com/hurst-shifter/PDF%20Files/instructionsheets/3737834.pdf?ck=Yzh2wTBXAVsREfwZ&vid=Yzh2wTBXAWAREbcl&cktime=87857)
What's the casting number on your side cover?

See above -- yup, the "stud" type trans has a smaller hole.
You can either "tweak" the arms you have (think dremel), get a 68- side cover (I think they're interchangeable?) or get the shift arms for the 69-72 kit.
Compare the 69-72 kit here:http://hurst-shifters.com/hurst-shifter/PDF%20Files/instructionsheets/3737834.pdf

You'll see that most parts are the same as the 64-68 kit, but the shift arms are different:
1-2 105 7058
3-4 105 7060
R 105 7059

<Mike types faster than me :)>

Thanks so much for all the help, as always on Team Chevelle!! I know what I need to do now.

for a Muncie 4 speed
1963 to 1968 is small slot stud mount
1969 to 1974 is large slot bolt mount