I’m going to swap in a 4-speed , what’s different from 350- 455?

I certainly understand that & if I wasn't planning on a nearly 100% stock "appearing" (i.e. concours) resto I'd already be figuring on a M23 and might still go that way. I was in Greg's shop & looked at his M23Z before he installed it & it looks reasonably stock appearing.

For Brent's (OP) Stage 2 build, I'd think that's definitely the way to go.

 

Definitely. The M23Z just looks like a slightly beefier Muncie. Not real obvious.

A Muncie can be built tougher but I think the beefed up case adds a lot of extra strength and head room to it. I was going to have my M21 rebuilt with the ultra-wide ratio gear set but nobody is selling them currently that I can find. It is something north of $800 for the gear set alone.

My M23Z with the factory linkage. Not a lot to give it away if you miss the AutoGear.


My M23Z from beneath the car.

 

I certainly like the M23 and if it looks stock enough I'd be inclined to go that route. Cost difference between a '70 M-21 core & rebuilding that & beefing it up isn't all that much. Looking forward to seeing yours installed.

 

Hey Knucklebusted what did you use for the 3-4 gear pivot bolt, my M22w came with a fine thread bolt but my pivot bolt is coarse thread?

 

I ground mine down and retapped it to the smaller thread.

I just replied to this. There's a local member that made a few of these. See his thread: 4 speed reverse light stud for an AutoGear trans | V8buick.com

 

Sorry but I don’t think that’ll work for me, the factory stud isn’t long enough to reach the threads inside the tranny even if I tap the correct fine threads. Would need another inch longer. If you look at the picture you’ll notice how much longer the supplied bolt is that screws all the way in. I called AutoGear and they had not seen this type of backup light application before. Here is how this guy solves it but it’s out-of-stock unfortunately.

 

Yes that’s how easy it is, if a guy has a drill press.

 

Until I find a solution I’ll just have to wait for now, but everything else is installed.

 

What washers Cjay?

 

Washers from where? It looks a lot like my M23Z so I'm curious what the issue is with washers.

 

Those were supplied by manufacture they have keepers slots that go into the lever making them square.

 

Ok I’ll look at it, that washer I may have added. Can you circle what you are talking about?